TextBox default template - wpf

I have a TextBox and when I hover it the border changing the color to blue. How can I disable this behavior ?
XAML:
<Canvas>
<Grid Canvas.Left="100" Canvas.Top="100" Width="200" Height="100">
<TextBox></TextBox>
</Grid>
</Canvas>

An easy "hack" you can use to disable the border animation when IsMouseOver is True is to make a small change to the BorderThickness. e.g BorderThickness="1.000001"
<Canvas>
<Grid Canvas.Left="100" Canvas.Top="100" Width="200" Height="100">
<TextBox BorderThickness="1.000001"/>
</Grid>
</Canvas>

you have to define a style where you remove the storyboard for the MouseOver state.
It should be like this (tested for SL):
<UserControl.Resources>
<Style x:Key="NoMouseOverTextBoxStyle" TargetType="TextBox">
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Background" Value="#FFFFFFFF"/>
<Setter Property="Foreground" Value="#FF000000"/>
<Setter Property="Padding" Value="2"/>
<Setter Property="BorderBrush">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFA3AEB9" Offset="0"/>
<GradientStop Color="#FF8399A9" Offset="0.375"/>
<GradientStop Color="#FF718597" Offset="0.375"/>
<GradientStop Color="#FF617584" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TextBox">
<Grid x:Name="RootElement">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver"/>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="DisabledVisualElement"/>
</Storyboard>
</VisualState>
<VisualState x:Name="ReadOnly">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="ReadOnlyVisualElement"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="FocusVisualElement"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused">
<Storyboard>
<DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="FocusVisualElement"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="ValidationStates">
<VisualState x:Name="Valid"/>
<VisualState x:Name="InvalidUnfocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ValidationErrorElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="InvalidFocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ValidationErrorElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsOpen" Storyboard.TargetName="validationTooltip">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>True</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="Border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" CornerRadius="1" Opacity="1">
<Grid>
<Border x:Name="ReadOnlyVisualElement" Background="#5EC9C9C9" Opacity="0"/>
<Border x:Name="MouseOverBorder" BorderBrush="Transparent" BorderThickness="1">
<ScrollViewer x:Name="ContentElement" BorderThickness="0" IsTabStop="False" Padding="{TemplateBinding Padding}"/>
</Border>
</Grid>
</Border>
<Border x:Name="DisabledVisualElement" BorderBrush="#A5F7F7F7" BorderThickness="{TemplateBinding BorderThickness}" Background="#A5F7F7F7" IsHitTestVisible="False" Opacity="0"/>
<Border x:Name="FocusVisualElement" BorderBrush="#FF6DBDD1" BorderThickness="{TemplateBinding BorderThickness}" IsHitTestVisible="False" Margin="1" Opacity="0"/>
<Border x:Name="ValidationErrorElement" BorderBrush="#FFDB000C" BorderThickness="1" CornerRadius="1" Visibility="Collapsed">
<ToolTipService.ToolTip>
<ToolTip x:Name="validationTooltip" DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}" Placement="Right" PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}" Template="{StaticResource ValidationToolTipTemplate}">
<ToolTip.Triggers>
<EventTrigger RoutedEvent="Canvas.Loaded">
<BeginStoryboard>
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsHitTestVisible" Storyboard.TargetName="validationTooltip">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>true</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</ToolTip.Triggers>
</ToolTip>
</ToolTipService.ToolTip>
<Grid Background="Transparent" HorizontalAlignment="Right" Height="12" Margin="1,-4,-4,0" VerticalAlignment="Top" Width="12">
<Path Data="M 1,0 L6,0 A 2,2 90 0 1 8,2 L8,7 z" Fill="#FFDC000C" Margin="1,3,0,0"/>
<Path Data="M 0,0 L2,0 L 8,6 L8,8" Fill="#ffffff" Margin="1,3,0,0"/>
</Grid>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</UserControl.Resources>
<Grid>
<TextBox Width="100" Height="100" Style="{StaticResource NoMouseOverTextBoxStyle}" />
</Grid>
If you want this for all text boxes, have a look at implicit styles (http://www.silverlightshow.net/items/Implicit-Styles-in-Silverlight-4.aspx).
BR,
TJ

Related

how to set vertical content alignment on a silverlight text box

I have a silverlight textbox which aligns all text to the center.
The VerticalContentAlignment does not work!
How can I align this text so that text starts on top and not in the center.
<StackPanel>
<TextBox Text="{Binding OverView,Mode=TwoWay}" AcceptsReturn="True"
Loaded="Update_EditableState"
Height="135" HorizontalAlignment="Left"
TextWrapping="Wrap" Width="200">
</TextBox>
</StackPanel>
As per Microsoft documentation VerticalContentAlignment does not work on the default template of text box.
To solve this we need our own style.
Adding binding verticalalignment to verticalcontentalignment of the template fixed the issue.
Here's the element i changed from the standard textbox style
<ScrollViewer x:Name="ContentElement" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Padding="{TemplateBinding Padding}" BorderThickness="0" IsTabStop="False"/>
Here's the complete style I used to achieve this
<Style x:Key="TextBoxWithVerticalContentAlignment" TargetType="TextBox">
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Background" Value="#FFFFFFFF"/>
<Setter Property="Foreground" Value="#FF000000"/>
<Setter Property="Padding" Value="2"/>
<Setter Property="BorderBrush">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFA3AEB9" Offset="0"/>
<GradientStop Color="#FF8399A9" Offset="0.375"/>
<GradientStop Color="#FF718597" Offset="0.375"/>
<GradientStop Color="#FF617584" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TextBox">
<Grid x:Name="RootElement">
<vsm:VisualStateManager.VisualStateGroups>
<vsm:VisualStateGroup x:Name="CommonStates">
<vsm:VisualState x:Name="Normal"/>
<vsm:VisualState x:Name="MouseOver">
<Storyboard>
<ColorAnimation Storyboard.TargetName="MouseOverBorder" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" To="#FF99C1E2" Duration="0"/>
</Storyboard>
</vsm:VisualState>
<vsm:VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="DisabledVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/>
</Storyboard>
</vsm:VisualState>
<vsm:VisualState x:Name="ReadOnly">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="ReadOnlyVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0" />
</Storyboard>
</vsm:VisualState>
</vsm:VisualStateGroup>
<vsm:VisualStateGroup x:Name="FocusStates">
<vsm:VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/>
</Storyboard>
</vsm:VisualState>
<vsm:VisualState x:Name="Unfocused">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity" To="0" Duration="0"/>
</Storyboard>
</vsm:VisualState>
</vsm:VisualStateGroup>
<vsm:VisualStateGroup x:Name="ValidationStates">
<vsm:VisualState x:Name="Valid"/>
<vsm:VisualState x:Name="InvalidUnfocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ValidationErrorElement" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</vsm:VisualState>
<vsm:VisualState x:Name="InvalidFocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ValidationErrorElement" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="validationTooltip" Storyboard.TargetProperty="IsOpen">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<sys:Boolean>True</sys:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</vsm:VisualState>
</vsm:VisualStateGroup>
</vsm:VisualStateManager.VisualStateGroups>
<Border x:Name="Border" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="1" Opacity="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}">
<Grid>
<Border x:Name="ReadOnlyVisualElement" Opacity="0" Background="#5EC9C9C9"/>
<Border x:Name="MouseOverBorder" Background="White" BorderThickness="1" BorderBrush="Transparent">
<ScrollViewer x:Name="ContentElement" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Padding="{TemplateBinding Padding}" BorderThickness="0" IsTabStop="False"/>
</Border>
</Grid>
</Border>
<Border x:Name="DisabledVisualElement" Background="#A5F7F7F7" BorderBrush="#A5F7F7F7" BorderThickness="{TemplateBinding BorderThickness}" Opacity="0" IsHitTestVisible="False"/>
<Border x:Name="FocusVisualElement" BorderBrush="#FF6DBDD1" BorderThickness="{TemplateBinding BorderThickness}" Margin="1" Opacity="0" IsHitTestVisible="False"/>
<Border x:Name="ValidationErrorElement" BorderThickness="1" CornerRadius="1" BorderBrush="#FFDB000C" Visibility="Collapsed">
<ToolTipService.ToolTip>
<ToolTip x:Name="validationTooltip" Template="{StaticResource ValidationToolTipTemplate}" Placement="Right"
PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}"
DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}">
<ToolTip.Triggers>
<EventTrigger RoutedEvent="Canvas.Loaded">
<EventTrigger.Actions>
<BeginStoryboard>
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="validationTooltip" Storyboard.TargetProperty="IsHitTestVisible">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<sys:Boolean>true</sys:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</ToolTip.Triggers>
</ToolTip>
</ToolTipService.ToolTip>
<Grid Width="12" Height="12" HorizontalAlignment="Right" Margin="1,-4,-4,0" VerticalAlignment="Top" Background="Transparent">
<Path Margin="1,3,0,0" Data="M 1,0 L6,0 A 2,2 90 0 1 8,2 L8,7 z" Fill="#FFDC000C"/>
<Path Margin="1,3,0,0" Data="M 0,0 L2,0 L 8,6 L8,8" Fill="#ffffff"/>
</Grid>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Much help was obtained from another question

Silverlight CheckBox

I want to change the background color of checkbox when its checked instead of show an icon but i have no idea of how to do this. I've tried to create a new "Rectangle" with a different background color and call him on VisualState "Checked" but it didnt work.
My code :
<Style TargetType="CheckBox">
<Setter Property="Background" Value="{StaticResource CheckBoxBackgroundBrush}" />
<Setter Property="BorderBrush" Value="{StaticResource CheckBoxBorderBrush}" />
<Setter Property="Foreground" Value="{StaticResource NormalFontBrush}" />
<Setter Property="HorizontalContentAlignment" Value="Left" />
<Setter Property="Padding" Value="6,1,0,0" />
<Setter Property="VerticalContentAlignment" Value="Center" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="CheckBox">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="13" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="MouseOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="MouseOverBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="PressedBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Duration="0" To=".55" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="contentPresenter" />
<DoubleAnimation Duration="0" To="0.55" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="DisabledVisualElement" />
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Checked">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="CheckIcon" />
</Storyboard>
</VisualState>
<VisualState x:Name="Unchecked" />
<VisualState x:Name="Indeterminate">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="IndeterminateIcon" />
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimation Duration="0" Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="(FrameworkElement.Opacity)" To="1" />
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused" />
</VisualStateGroup>
<VisualStateGroup x:Name="ValidationStates">
<VisualState x:Name="Valid" />
<VisualState x:Name="InvalidUnfocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ValidationErrorElement">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="InvalidFocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ValidationErrorElement">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsOpen" Storyboard.TargetName="validationTooltip">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>True</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Grid Height="12" HorizontalAlignment="Left" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Width="12">
<Rectangle x:Name="Background" Fill="{TemplateBinding Background}" Height="12" Stroke="{TemplateBinding BorderBrush}" Width="12" />
<Border x:Name="OuterHighlight" BorderBrush="{StaticResource ControlOuterHighlightBrush}" BorderThickness="0,0,1,1" CornerRadius="1,0,1,0" Margin="1,1,-1,-1" />
<Border x:Name="InnerShadow" BorderBrush="{StaticResource CheckBoxInnerShadowBrush}" BorderThickness="1,1,0,0" CornerRadius="0.5" Margin="1,1,0,0" />
<Border x:Name="MouseOverBorder" BorderBrush="{StaticResource ColorAccentBrush}" BorderThickness="1" Margin="1" Visibility="Collapsed" />
<Border x:Name="PressedBorder" BorderBrush="{StaticResource ColorAccentSubduedBrush}" BorderThickness="1" Margin="1" Visibility="Collapsed" />
<Path x:Name="CheckIcon" Data="M0.5625,5.0625 L1.5,3.9375 L2.9575791,4.9549685 C2.9575791,4.9549685 5.75,1.125 5.75,1.125 C5.75,1.125 6.9375,2 6.9375,2 C6.9375,2 3.186887,7.0000076 3.186887,7.0000076 z" Fill="{StaticResource CheckBoxColorAccentHighlightBrush}" FlowDirection="LeftToRight" Margin="2,2,0,1" Opacity="0"/>
<Rectangle x:Name="IndeterminateIcon" Fill="{StaticResource ColorAccentHighlightBrush}" Height="2" Opacity="0" Width="6" />
<Rectangle x:Name="DisabledVisualElement" Fill="{StaticResource DisabledBrush}" Height="12" Opacity="0" Width="12" />
<Rectangle x:Name="FocusVisualElement" IsHitTestVisible="False" Margin="2" Opacity="0" Stroke="{StaticResource FocusVisualBrush}" StrokeThickness="{StaticResource FocusVisualStrokeThickness}" />
<Border x:Name="ValidationErrorElement" BorderBrush="{StaticResource ErrorBrush}" BorderThickness="1" Margin="1" ToolTipService.PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}" Visibility="Collapsed">
<ToolTipService.ToolTip>
<ToolTip x:Name="validationTooltip" DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}" Placement="Right" PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}" Template="{StaticResource ValidationToolTipTemplate}">
<ToolTip.Triggers>
<EventTrigger RoutedEvent="Canvas.Loaded">
<BeginStoryboard>
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsHitTestVisible" Storyboard.TargetName="validationTooltip">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>true</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</ToolTip.Triggers>
</ToolTip>
</ToolTipService.ToolTip>
<Grid Background="Transparent" HorizontalAlignment="Right" Height="10" Margin="0,-4,-4,0" VerticalAlignment="Top" Width="10">
<Path Data="M 1,0 L5,0 A 2,2 90 0 1 7,2 L7,6 z" Fill="{StaticResource ErrorBrush}" Margin="0,3,0,0" />
</Grid>
</Border>
</Grid>
<ContentPresenter x:Name="contentPresenter" Content="{TemplateBinding Content}" ContentTemplate="{TemplateBinding ContentTemplate}" Grid.Column="1" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" />
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Thanks!
You are on the right track. Create a rectangle (or border) with the desired background color and Opacity 0. In the Checked state, animate the Opacity to 1. Alternatively, set the Visibility to Collapsed and animate visibility similar to how the PressedBorder element is animated in the Pressed state.
Under PressedBorder
<Border x:Name="CheckedBorder" BorderThickness="1" Margin="1" Background="Green" Visibility="Collapsed" />
In VSM:
<VisualState x:Name="Pressed">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="PressedBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>

Visual States or Silverlight ComboBox

I'm trying to modify a siverlight combobox so that the "combo" part is ony visible when accessed. I changed the Opacity of the DropDownToggle part to 0 and changed the MouseOver Visual State to set the opcaity of the DropDownToggle to 50%.
This works fine, until I select an item in the control. Once I select an item, the Opacity of the DropDownToggle is fixed to 50% permanently, and I (apparently) can't get the combo to revert back to the "normal" visual state.
One more interesting visual artifact is that the control still responds to mouseovers as the gradient background changes when I mouse the control - it just never reverts back to "normal".
Any feedback is appreciated
Here's the XAML as requested - thanks!
<UserControl.Resources>
<ControlTemplate x:Key="ValidationToolTipTemplate">
<Grid x:Name="Root" Margin="5,0" Opacity="0" RenderTransformOrigin="0,0">
<Grid.RenderTransform>
<TranslateTransform x:Name="xform" X="-25"/>
</Grid.RenderTransform>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="OpenStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0"/>
<VisualTransition GeneratedDuration="0:0:0.2" To="Open">
<Storyboard>
<DoubleAnimation Duration="0:0:0.2" To="0" Storyboard.TargetProperty="X" Storyboard.TargetName="xform">
<DoubleAnimation.EasingFunction>
<BackEase Amplitude=".3" EasingMode="EaseOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
<DoubleAnimation Duration="0:0:0.2" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="Root"/>
</Storyboard>
</VisualTransition>
</VisualStateGroup.Transitions>
<VisualState x:Name="Closed">
<Storyboard>
<DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="Root"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Open">
<Storyboard>
<DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="X" Storyboard.TargetName="xform"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="Root"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border Background="#052A2E31" CornerRadius="5" Margin="4,4,-4,-4"/>
<Border Background="#152A2E31" CornerRadius="4" Margin="3,3,-3,-3"/>
<Border Background="#252A2E31" CornerRadius="3" Margin="2,2,-2,-2"/>
<Border Background="#352A2E31" CornerRadius="2" Margin="1,1,-1,-1"/>
<Border Background="#FFDC000C" CornerRadius="2"/>
<Border CornerRadius="2">
<TextBlock Foreground="White" MaxWidth="250" Margin="8,4,8,4" TextWrapping="Wrap" Text="{Binding (Validation.Errors)[0].ErrorContent}" UseLayoutRounding="false"/>
</Border>
</Grid>
</ControlTemplate>
<Style x:Key="TextStyle" TargetType="TextBlock" >
<Setter Property="HorizontalAlignment" Value="Left"/>
<Setter Property="TextWrapping" Value="NoWrap" />
<Setter Property="Padding" Value="0,4,0,2" />
<Setter Property="FontSize" Value="32"/>
<Setter Property="FontFamily" Value="Arial"/>
</Style>
<Style x:Key="InteractiveLabelComboBoxItemStyle" TargetType="ComboBoxItem">
<Setter Property="Padding" Value="3"/>
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="VerticalContentAlignment" Value="Top"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="TabNavigation" Value="Local"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBoxItem">
<Grid Background="{TemplateBinding Background}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver">
<Storyboard>
<DoubleAnimation Duration="0" To=".35" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="fillColor"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Duration="0" To=".55" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="contentPresenter"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="SelectionStates">
<VisualState x:Name="Unselected"/>
<VisualState x:Name="Selected">
<Storyboard>
<DoubleAnimation Duration="0" To=".75" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="fillColor2"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="0" Storyboard.TargetProperty="Visibility" Storyboard.TargetName="FocusVisualElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Rectangle x:Name="fillColor" Fill="#FFBADDE9" IsHitTestVisible="False" Opacity="0" RadiusY="1" RadiusX="1"/>
<Rectangle x:Name="fillColor2" Fill="#FFBADDE9" IsHitTestVisible="False" Opacity="0" RadiusY="1" RadiusX="1"/>
<ContentPresenter x:Name="contentPresenter" ContentTemplate="{TemplateBinding ContentTemplate}" Content="{TemplateBinding Content}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}"/>
<Rectangle x:Name="FocusVisualElement" RadiusY="1" RadiusX="1" Stroke="#FF6DBDD1" StrokeThickness="1" Visibility="Collapsed"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="FontFamily" Value="Arial"/>
<Setter Property="FontSize" Value="32"/>
</Style>
<Style x:Key="InteractiveLabel" TargetType="ComboBox">
<Setter Property="FontSize" Value="32"/>
<Setter Property="FontFamily" Value="Arial"/>
<Setter Property="Padding" Value="6,2,25,2"/>
<Setter Property="Background" Value="#FF1F3B53"/>
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="TabNavigation" Value="Once"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="BorderBrush">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFA3AEB9" Offset="0"/>
<GradientStop Color="#FF8399A9" Offset="0.375"/>
<GradientStop Color="#FF718597" Offset="0.375"/>
<GradientStop Color="#FF617584" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBox">
<Grid>
<Grid.RenderTransform>
<TranslateTransform Y="10"/>
</Grid.RenderTransform>
<Grid.Resources>
<Style x:Name="comboToggleStyle" TargetType="ToggleButton">
<Setter Property="Foreground" Value="#FF333333"/>
<Setter Property="Background" Value="#FF1F3B53"/>
<Setter Property="BorderBrush">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFA3AEB9" Offset="0"/>
<GradientStop Color="#FF8399A9" Offset="0.375"/>
<GradientStop Color="#FF718597" Offset="0.375"/>
<GradientStop Color="#FF617584" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Padding" Value="3"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToggleButton">
<Grid>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="BackgroundOverlay"/>
<ColorAnimation Duration="0" To="#7FFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[3].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#CCFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[2].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#F2FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="BackgroundOverlay2"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="Highlight"/>
<ColorAnimation Duration="0" To="#E5FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#BCFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[2].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#6BFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[3].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#F2FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[0].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled"/>
</VisualStateGroup>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Checked">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="BackgroundOverlay3"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="Highlight"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="BackgroundGradient2"/>
<ColorAnimation Duration="0" To="#E5FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient2"/>
<ColorAnimation Duration="0" To="#BCFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[2].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient2"/>
<ColorAnimation Duration="0" To="#6BFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[3].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient2"/>
<ColorAnimation Duration="0" To="#F2FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[0].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient2"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Unchecked"/>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="0" Storyboard.TargetProperty="Visibility" Storyboard.TargetName="FocusVisualElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Rectangle x:Name="Background" Fill="{TemplateBinding Background}" RadiusY="3" RadiusX="3" Stroke="{TemplateBinding BorderBrush}" StrokeThickness="{TemplateBinding BorderThickness}"/>
<Rectangle x:Name="BackgroundOverlay" Fill="#FF448DCA" Opacity="0" RadiusY="3" RadiusX="3" Stroke="#00000000" StrokeThickness="{TemplateBinding BorderThickness}"/>
<Rectangle x:Name="BackgroundOverlay2" Fill="#FF448DCA" Opacity="0" RadiusY="3" RadiusX="3" Stroke="#00000000" StrokeThickness="{TemplateBinding BorderThickness}"/>
<Rectangle x:Name="BackgroundGradient" Margin="{TemplateBinding BorderThickness}" RadiusY="2" RadiusX="2" Stroke="#FFFFFFFF" StrokeThickness="1">
<Rectangle.Fill>
<LinearGradientBrush EndPoint=".7,1" StartPoint=".7,0">
<GradientStop Color="#FFFFFFFF" Offset="0"/>
<GradientStop Color="#F9FFFFFF" Offset="0.375"/>
<GradientStop Color="#E5FFFFFF" Offset="0.625"/>
<GradientStop Color="#C6FFFFFF" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<Rectangle x:Name="BackgroundOverlay3" Fill="#FF448DCA" Opacity="0" RadiusY="3" RadiusX="3" Stroke="#00000000" StrokeThickness="{TemplateBinding BorderThickness}"/>
<Rectangle x:Name="BackgroundGradient2" Margin="{TemplateBinding BorderThickness}" Opacity="0" RadiusY="2" RadiusX="2" Stroke="#FFFFFFFF" StrokeThickness="1">
<Rectangle.Fill>
<LinearGradientBrush EndPoint=".7,1" StartPoint=".7,0">
<GradientStop Color="#FFFFFFFF" Offset="0"/>
<GradientStop Color="#F9FFFFFF" Offset="0.375"/>
<GradientStop Color="#E5FFFFFF" Offset="0.625"/>
<GradientStop Color="#C6FFFFFF" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<Rectangle x:Name="Highlight" IsHitTestVisible="false" Margin="{TemplateBinding BorderThickness}" Opacity="0" RadiusY="2" RadiusX="2" Stroke="#FF6DBDD1" StrokeThickness="1"/>
<ContentPresenter x:Name="contentPresenter" ContentTemplate="{TemplateBinding ContentTemplate}" Content="{TemplateBinding Content}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
<Rectangle x:Name="FocusVisualElement" IsHitTestVisible="false" Margin="1" RadiusY="3.5" RadiusX="3.5" Stroke="#FF6DBDD1" StrokeThickness="1" Visibility="Collapsed"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Grid.Resources>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal">
<Storyboard>
<DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="DropDownToggle" d:IsOptimized="True"/>
</Storyboard>
</VisualState>
<VisualState x:Name="MouseOver">
<Storyboard>
<DoubleAnimation Duration="0" To="0.5" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="DropDownToggle" d:IsOptimized="True"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Duration="00:00:00" To=".55" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="DisabledVisualElement"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimation Duration="00:00:00" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="FocusVisualElement"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
<VisualState x:Name="FocusedDropDown">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="00:00:00" Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="PopupBorder">
<DiscreteObjectKeyFrame KeyTime="00:00:00">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="ValidationStates">
<VisualState x:Name="Valid"/>
<VisualState x:Name="InvalidUnfocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ValidationErrorElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="InvalidFocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ValidationErrorElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsOpen" Storyboard.TargetName="validationTooltip">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>True</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="ContentPresenterBorder">
<Grid >
<ToggleButton x:Name="DropDownToggle" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" HorizontalAlignment="Stretch" HorizontalContentAlignment="Right" Margin="0" Style="{StaticResource comboToggleStyle}" VerticalAlignment="Stretch" Opacity="0">
<Path x:Name="BtnArrow" Data="F1 M 301.14,-189.041L 311.57,-189.041L 306.355,-182.942L 301.14,-189.041 Z " HorizontalAlignment="Right" Height="4" Margin="0,0,6,0" Stretch="Uniform" Width="8">
<Path.Fill>
<SolidColorBrush x:Name="BtnArrowColor" Color="#FF333333"/>
</Path.Fill>
</Path>
</ToggleButton>
<ContentPresenter x:Name="ContentPresenter" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
<TextBlock Style="{StaticResource TextStyle}" Text="DefaultText" Padding="0,0,0,0"/>
</ContentPresenter>
</Grid>
</Border>
<Rectangle x:Name="DisabledVisualElement" Fill="White" IsHitTestVisible="false" Opacity="0" RadiusY="3" RadiusX="3"/>
<Rectangle x:Name="FocusVisualElement" IsHitTestVisible="false" Margin="1" Opacity="0" RadiusY="2" RadiusX="2" Stroke="#FF6DBDD1" StrokeThickness="1"/>
<Border x:Name="ValidationErrorElement" BorderBrush="#FFDB000C" BorderThickness="1" CornerRadius="1" Visibility="Collapsed">
<ToolTipService.ToolTip>
<ToolTip x:Name="validationTooltip" DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}" Placement="Right" PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}" Template="{StaticResource ValidationToolTipTemplate}">
<ToolTip.Triggers>
<EventTrigger RoutedEvent="Canvas.Loaded">
<BeginStoryboard>
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsHitTestVisible" Storyboard.TargetName="validationTooltip">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>true</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</ToolTip.Triggers>
</ToolTip>
</ToolTipService.ToolTip>
<Grid Background="Transparent" HorizontalAlignment="Right" Height="12" Margin="1,-4,-4,0" VerticalAlignment="Top" Width="12">
<Path Data="M 1,0 L6,0 A 2,2 90 0 1 8,2 L8,7 z" Fill="#FFDC000C" Margin="1,3,0,0"/>
<Path Data="M 0,0 L2,0 L 8,6 L8,8" Fill="#ffffff" Margin="1,3,0,0"/>
</Grid>
</Border>
<Popup x:Name="Popup">
<Border x:Name="PopupBorder" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="3" HorizontalAlignment="Stretch" Height="Auto">
<Border.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFFFFFFF" Offset="0"/>
<GradientStop Color="#FFFEFEFE" Offset="1"/>
</LinearGradientBrush>
</Border.Background>
<ScrollViewer x:Name="ScrollViewer" BorderThickness="0" Padding="1">
<ItemsPresenter/>
</ScrollViewer>
</Border>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</UserControl.Resources>
<Grid x:Name="LayoutRoot" Background="Transparent" HorizontalAlignment="Center" VerticalAlignment="Center">
<RichTextBox Background="Transparent" HorizontalAlignment="Left" Margin="10,12,0,5" x:Name="contentBox"
VerticalAlignment="Top" IsReadOnly="True" Cursor="Arrow" IsTabStop="False" BorderBrush="{x:Null}">
<Paragraph FontSize="32" FontFamily="Arial" TextAlignment="Center"><Run Text="Selection for "/><InlineUIContainer>
<ComboBox Style="{StaticResource InteractiveLabel}" >
<ComboBoxItem Content="Default Value" />
</ComboBox>
</InlineUIContainer></Paragraph>
</RichTextBox>
</Grid>

Force ComboBox to open up in Silverlight?

I have a ComboBox in Silverlight that has very inconsistent behavior.
I have the ComboBox bound to a dynamic collection of data where elements are added or removed. Here is the XAML for the ComboBox:
<ComboBox Margin="0,-1,0,0" Width="20" Grid.Row="0" Grid.Column="0" ItemsSource="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=ItemsContained}" x:Name="TabComboBox" >
<ComboBox.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Background="White" MinWidth="250" />
</ItemsPanelTemplate>
</ComboBox.ItemsPanel>
</ComboBox>
So this works great and the ComboBox opens "up" with the long list of items in ItemsContained. However, if I delete one of the items in ItemsContained, the ComboBox all of a sudden will switch from opening "up" to opening "down" when you click on it, despite the fact there are a lot of items in this collection and there is only 20 or so pixels of room for it to open down. I cannot figure this out. I have even tried setting the ItemsPanelTemplate to have a MinHeight, but that does not help. Does anyone know how to make the ComboBox always open "up"?
Also, even if I set the MinHeight to something ridiculous, such as 10,000, it still does this.
EDIT: As an update, I have gotten this to work by creating a whole new ComboBox every time ItemsContained is changed. This is the code:
scrollingGrid.Children.Remove(tabComboBox);
tabComboBox.ItemsSource = null;
ComboBox boxy = new ComboBox()
{
ItemsSource = ItemsContained
};
scrollingGrid.Children.Add(boxy);
tabComboBox = boxy;
I feel this is a little ad hoc, so if anyone has a better idea, let me know. Changing the height of the ScrollViewer inside the ComboBox does not work either.
I think this is a Silverlight Bug. When you set the ItemsSource property the behavior of the combobox popup changes from up to down.
I Clone my combobox in the event DropDownClosed of each combobox and that works for me.
Private Sub cbRow1_DropDownClosed(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbRow1.DropDownClosed, cbRow2.DropDownClosed, cbRow3.DropDownClosed, cbRow4.DropDownClosed, cbRow5.DropDownClosed
Dim co As ComboBox = CType(sender, ComboBox)
CloneComboBox(co)
End Sub
Private Sub CloneComboBox(ByVal co As ComboBox)
Dim cbClon = New ComboBox()
cbClon.Margin = co.Margin
cbClon.Width = co.Width
cbClon.Height = co.Height
cbClon.Name = co.Name
cbClon.Tag = co.Tag
cbClon.ItemsSource = co.ItemsSource
cbClon.SelectedIndex = co.SelectedIndex
LayoutRoot.Children.Remove(co)
LayoutRoot.Children.Add(cbClon)
//this is because I have my comboboxes inside a grid
System.Windows.Controls.Grid.SetRow(cbClon, cbClon.Tag)
System.Windows.Controls.Grid.SetColumn(cbClon, 0)
AddHandler cbClon.DropDownClosed, AddressOf cbRow1_DropDownClosed
End Sub
I'm not sure this solution will be any less ad hoc than your current fix, but I figured I'd offer it.
I edited a copy of the ComboBox template, and where the original only had a ScrollViewer in an ItemsPresenter, I added a Rectangle with Margin 0,5000,0,0, so that the internal Popup code would place it on the top always. I also moved the template bindings to the ScrollViewer so that it wouldn't stretch to the top even if there weren't enough items.
The style is a little long but here it is, just throw it in your resources xaml (and set the style of your ComboBox to ComboBoxStyle1). Let me know how it works for you!
<ControlTemplate x:Key="ValidationToolTipTemplate">
<Grid x:Name="Root" Margin="5,0" Opacity="0" RenderTransformOrigin="0,0">
<Grid.RenderTransform>
<TranslateTransform x:Name="xform" X="-25"/>
</Grid.RenderTransform>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="OpenStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0"/>
<VisualTransition GeneratedDuration="0:0:0.2" To="Open">
<Storyboard>
<DoubleAnimation Duration="0:0:0.2" To="0" Storyboard.TargetProperty="X" Storyboard.TargetName="xform">
<DoubleAnimation.EasingFunction>
<BackEase Amplitude=".3" EasingMode="EaseOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
<DoubleAnimation Duration="0:0:0.2" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="Root"/>
</Storyboard>
</VisualTransition>
</VisualStateGroup.Transitions>
<VisualState x:Name="Closed">
<Storyboard>
<DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="Root"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Open">
<Storyboard>
<DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="X" Storyboard.TargetName="xform"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="Root"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border Background="#052A2E31" CornerRadius="5" Margin="4,4,-4,-4"/>
<Border Background="#152A2E31" CornerRadius="4" Margin="3,3,-3,-3"/>
<Border Background="#252A2E31" CornerRadius="3" Margin="2,2,-2,-2"/>
<Border Background="#352A2E31" CornerRadius="2" Margin="1,1,-1,-1"/>
<Border Background="#FFDC000C" CornerRadius="2"/>
<Border CornerRadius="2">
<TextBlock Foreground="White" MaxWidth="250" Margin="8,4,8,4" TextWrapping="Wrap" Text="{Binding (Validation.Errors)[0].ErrorContent}" UseLayoutRounding="false"/>
</Border>
</Grid>
</ControlTemplate>
<Style x:Key="ComboBoxStyle1" TargetType="ComboBox">
<Setter Property="Padding" Value="6,2,25,2"/>
<Setter Property="Background" Value="#FF1F3B53"/>
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="TabNavigation" Value="Once"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="BorderBrush">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFA3AEB9" Offset="0"/>
<GradientStop Color="#FF8399A9" Offset="0.375"/>
<GradientStop Color="#FF718597" Offset="0.375"/>
<GradientStop Color="#FF617584" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBox">
<Grid>
<Grid.Resources>
<Style x:Name="comboToggleStyle" TargetType="ToggleButton">
<Setter Property="Foreground" Value="#FF333333"/>
<Setter Property="Background" Value="#FF1F3B53"/>
<Setter Property="BorderBrush">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFA3AEB9" Offset="0"/>
<GradientStop Color="#FF8399A9" Offset="0.375"/>
<GradientStop Color="#FF718597" Offset="0.375"/>
<GradientStop Color="#FF617584" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Padding" Value="3"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToggleButton">
<Grid>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="BackgroundOverlay"/>
<ColorAnimation Duration="0" To="#7FFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[3].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#CCFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[2].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#F2FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="BackgroundOverlay2"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="Highlight"/>
<ColorAnimation Duration="0" To="#E5FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#BCFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[2].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#6BFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[3].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
<ColorAnimation Duration="0" To="#F2FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[0].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled"/>
</VisualStateGroup>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Checked">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="BackgroundOverlay3"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="Highlight"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="BackgroundGradient2"/>
<ColorAnimation Duration="0" To="#E5FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient2"/>
<ColorAnimation Duration="0" To="#BCFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[2].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient2"/>
<ColorAnimation Duration="0" To="#6BFFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[3].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient2"/>
<ColorAnimation Duration="0" To="#F2FFFFFF" Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[0].(GradientStop.Color)" Storyboard.TargetName="BackgroundGradient2"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Unchecked"/>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="0" Storyboard.TargetProperty="Visibility" Storyboard.TargetName="FocusVisualElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Rectangle x:Name="Background" Fill="{TemplateBinding Background}" RadiusY="3" RadiusX="3" Stroke="{TemplateBinding BorderBrush}" StrokeThickness="{TemplateBinding BorderThickness}"/>
<Rectangle x:Name="BackgroundOverlay" Fill="#FF448DCA" Opacity="0" RadiusY="3" RadiusX="3" Stroke="#00000000" StrokeThickness="{TemplateBinding BorderThickness}"/>
<Rectangle x:Name="BackgroundOverlay2" Fill="#FF448DCA" Opacity="0" RadiusY="3" RadiusX="3" Stroke="#00000000" StrokeThickness="{TemplateBinding BorderThickness}"/>
<Rectangle x:Name="BackgroundGradient" Margin="{TemplateBinding BorderThickness}" RadiusY="2" RadiusX="2" Stroke="#FFFFFFFF" StrokeThickness="1">
<Rectangle.Fill>
<LinearGradientBrush EndPoint=".7,1" StartPoint=".7,0">
<GradientStop Color="#FFFFFFFF" Offset="0"/>
<GradientStop Color="#F9FFFFFF" Offset="0.375"/>
<GradientStop Color="#E5FFFFFF" Offset="0.625"/>
<GradientStop Color="#C6FFFFFF" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<Rectangle x:Name="BackgroundOverlay3" Fill="#FF448DCA" Opacity="0" RadiusY="3" RadiusX="3" Stroke="#00000000" StrokeThickness="{TemplateBinding BorderThickness}"/>
<Rectangle x:Name="BackgroundGradient2" Margin="{TemplateBinding BorderThickness}" Opacity="0" RadiusY="2" RadiusX="2" Stroke="#FFFFFFFF" StrokeThickness="1">
<Rectangle.Fill>
<LinearGradientBrush EndPoint=".7,1" StartPoint=".7,0">
<GradientStop Color="#FFFFFFFF" Offset="0"/>
<GradientStop Color="#F9FFFFFF" Offset="0.375"/>
<GradientStop Color="#E5FFFFFF" Offset="0.625"/>
<GradientStop Color="#C6FFFFFF" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<Rectangle x:Name="Highlight" IsHitTestVisible="false" Margin="{TemplateBinding BorderThickness}" Opacity="0" RadiusY="2" RadiusX="2" Stroke="#FF6DBDD1" StrokeThickness="1"/>
<ContentPresenter x:Name="contentPresenter" ContentTemplate="{TemplateBinding ContentTemplate}" Content="{TemplateBinding Content}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
<Rectangle x:Name="FocusVisualElement" IsHitTestVisible="false" Margin="1" RadiusY="3.5" RadiusX="3.5" Stroke="#FF6DBDD1" StrokeThickness="1" Visibility="Collapsed"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Grid.Resources>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver"/>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Duration="00:00:00" To=".55" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="DisabledVisualElement"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimation Duration="00:00:00" To="1" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="FocusVisualElement"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
<VisualState x:Name="FocusedDropDown">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="00:00:00" Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="PopupBorder">
<DiscreteObjectKeyFrame KeyTime="00:00:00">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="ValidationStates">
<VisualState x:Name="Valid"/>
<VisualState x:Name="InvalidUnfocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ValidationErrorElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="InvalidFocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="ValidationErrorElement">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsOpen" Storyboard.TargetName="validationTooltip">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>True</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="ContentPresenterBorder">
<Grid>
<ToggleButton x:Name="DropDownToggle" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" HorizontalAlignment="Stretch" HorizontalContentAlignment="Right" Margin="0" Style="{StaticResource comboToggleStyle}" VerticalAlignment="Stretch">
<Path x:Name="BtnArrow" Data="F1 M 301.14,-189.041L 311.57,-189.041L 306.355,-182.942L 301.14,-189.041 Z " HorizontalAlignment="Right" Height="4" Margin="0,0,6,0" Stretch="Uniform" Width="8">
<Path.Fill>
<SolidColorBrush x:Name="BtnArrowColor" Color="#FF333333"/>
</Path.Fill>
</Path>
</ToggleButton>
<ContentPresenter x:Name="ContentPresenter" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
<TextBlock Text=" "/>
</ContentPresenter>
</Grid>
</Border>
<Rectangle x:Name="DisabledVisualElement" Fill="White" IsHitTestVisible="false" Opacity="0" RadiusY="3" RadiusX="3"/>
<Rectangle x:Name="FocusVisualElement" IsHitTestVisible="false" Margin="1" Opacity="0" RadiusY="2" RadiusX="2" Stroke="#FF6DBDD1" StrokeThickness="1"/>
<Border x:Name="ValidationErrorElement" BorderBrush="#FFDB000C" BorderThickness="1" CornerRadius="1" Visibility="Collapsed">
<ToolTipService.ToolTip>
<ToolTip x:Name="validationTooltip" DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}" Placement="Right" PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}" Template="{StaticResource ValidationToolTipTemplate}">
<ToolTip.Triggers>
<EventTrigger RoutedEvent="Canvas.Loaded">
<BeginStoryboard>
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsHitTestVisible" Storyboard.TargetName="validationTooltip">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<System:Boolean>true</System:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</ToolTip.Triggers>
</ToolTip>
</ToolTipService.ToolTip>
<Grid Background="Transparent" HorizontalAlignment="Right" Height="12" Margin="1,-4,-4,0" VerticalAlignment="Top" Width="12">
<Path Data="M 1,0 L6,0 A 2,2 90 0 1 8,2 L8,7 z" Fill="#FFDC000C" Margin="1,3,0,0"/>
<Path Data="M 0,0 L2,0 L 8,6 L8,8" Fill="#ffffff" Margin="1,3,0,0"/>
</Grid>
</Border>
<Popup x:Name="Popup" >
<Border x:Name="PopupBorder" HorizontalAlignment="Stretch">
<Grid>
<ScrollViewer BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" VerticalAlignment="Bottom" x:Name="ScrollViewer" Padding="1">
<ScrollViewer.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="White" Offset="0"/>
<GradientStop Color="#FFFEFEFE" Offset="1"/>
</LinearGradientBrush>
</ScrollViewer.Background>
<ItemsPresenter/>
</ScrollViewer>
<Rectangle Margin="0,5000,0,0"/>
</Grid>
</Border>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

Custom expand/collapse symbols in Silverlight TreeView using HierarchicalDataTemplate

I have a TreeView control where nodes are dynamically built using a HierarchicalDataTemplate. In other words, no TreeViewItems are explicitly defined in the XAML. TreeViewItems are instead created automatically when the data are bound at runtime (I can see them in Silverlight Spy).
Is it possible to customize the expand/collapse symbols (paths) within the TreeView in this case? Clients hate the default triangles as being hard to see and use. I've found references to doing this kind of thing, but only where the TreeViewItems are set up explicitly, so that a Style can be set in the XAML of the page. Another way of asking this I guess is whether it's possible to define and apply a style for the TreeViewItem when they are not in the XAML markup (or added in code as TreeViewItem).
Yes, you will need to change the TreeViewItem's style property. Here is one I'm using...
<Style x:Key="TreeViewContainerStyle" TargetType="controls:TreeViewItem">
<Setter Property="Padding" Value="3"/>
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="VerticalContentAlignment" Value="Top"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Foreground"
Value="Black" />
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Cursor" Value="Arrow"/>
<Setter Property="Margin" Value="-5,0,0,0"/>
<Setter Property="IsTabStop" Value="True"/>
<Setter Property="TabNavigation" Value="Once"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="controls:TreeViewItem">
<Grid Background="{x:Null}">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="25"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="25"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="Disabled">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="0" Storyboard.TargetName="Header" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<SolidColorBrush Color="#FF999999"/>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="MouseOver">
<Storyboard>
<ColorAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="ExpanderButton" Storyboard.TargetProperty="(Control.Background).(SolidColorBrush.Color)">
<EasingColorKeyFrame KeyTime="00:00:00" Value="#FF90B5D5"/>
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="SelectionStates">
<VisualState x:Name="Unselected"/>
<VisualState x:Name="Selected">
<Storyboard>
<DoubleAnimation Duration="0" Storyboard.TargetName="select" Storyboard.TargetProperty="Opacity" To=".75"/>
</Storyboard>
</VisualState>
<VisualState x:Name="SelectedInactive">
<Storyboard>
<DoubleAnimation Duration="0" Storyboard.TargetName="inactive" Storyboard.TargetProperty="Opacity" To=".2"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="HasItemsStates">
<VisualState x:Name="HasItems"/>
<VisualState x:Name="NoItems">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="0" Storyboard.TargetName="ExpanderButton" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="ExpansionStates">
<VisualState x:Name="Collapsed"/>
<VisualState x:Name="Expanded">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="0" Storyboard.TargetName="ItemsHost" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<ToggleButton x:Name="ExpanderButton" IsTabStop="False" TabNavigation="Once" HorizontalAlignment="Stretch">
<ToggleButton.Template>
<ControlTemplate TargetType="ToggleButton">
<Grid x:Name="Root" Background="Transparent" Opacity=".6">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver">
<Storyboard>
<DoubleAnimation Duration="0" Storyboard.TargetName="Root" Storyboard.TargetProperty="Opacity" To="1.7"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Duration="0" Storyboard.TargetName="Root" Storyboard.TargetProperty="Opacity" To="1.7"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Unchecked"/>
<VisualState x:Name="Checked">
<Storyboard>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="MinusSign" Storyboard.TargetProperty="(UIElement.Opacity)">
<EasingDoubleKeyFrame KeyTime="00:00:00" Value="1"/>
</DoubleAnimationUsingKeyFrames>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="PlusSign" Storyboard.TargetProperty="(UIElement.Opacity)">
<EasingDoubleKeyFrame KeyTime="00:00:00" Value="0"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Grid>
<Rectangle x:Name="PlusSign" HorizontalAlignment="Center" VerticalAlignment="Top" Width="20" Height="20" Visibility="Visible" Opacity="100">
<Rectangle.Fill>
<ImageBrush Stretch="Fill" ImageSource="./icon_expand_hover.png"/>
</Rectangle.Fill>
</Rectangle>
<Rectangle x:Name="MinusSign" HorizontalAlignment="Center" VerticalAlignment="Top" Width="20" Height="20" Visibility="Visible" Opacity="0">
<Rectangle.Fill>
<ImageBrush Stretch="Fill" ImageSource="./icon_collapse_hover.png"/>
</Rectangle.Fill>
</Rectangle>
</Grid>
</Grid>
</ControlTemplate>
</ToggleButton.Template>
</ToggleButton>
<Rectangle x:Name="select" StrokeThickness="1" RadiusX="2" RadiusY="2" IsHitTestVisible="False" Opacity="0" Grid.Column="1" HorizontalAlignment="Stretch" Width="Auto" Margin="0,0,5,0">
<Rectangle.Stroke>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#00000000"/>
<GradientStop Color="#7F000000" Offset="1"/>
<GradientStop Color="#06000000" Offset="0.379"/>
</LinearGradientBrush>
</Rectangle.Stroke>
<Rectangle.Fill>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#00000000"/>
<GradientStop Color="#7F000000" Offset="1"/>
<GradientStop Color="#06000000" Offset="0.659"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<Rectangle x:Name="inactive" Fill="#FF999999" Stroke="#FF333333" StrokeThickness="1" RadiusX="2" RadiusY="2" IsHitTestVisible="False" Opacity="0" Grid.Column="1" HorizontalAlignment="Left" Width="6"/>
<Button x:Name="Header" Cursor="{TemplateBinding Cursor}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Background="{TemplateBinding Background}" Foreground="{TemplateBinding Foreground}" IsTabStop="False" TabNavigation="Once" ClickMode="Hover" Content="{TemplateBinding Header}" ContentTemplate="{TemplateBinding HeaderTemplate}" Grid.Column="1">
<Button.Template>
<ControlTemplate TargetType="Button">
<Grid Background="{TemplateBinding Background}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="Pressed">
<Storyboard>
<DoubleAnimation Duration="0" Storyboard.TargetName="hover" Storyboard.TargetProperty="Opacity" To=".5"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Duration="0" Storyboard.TargetName="content" Storyboard.TargetProperty="Opacity" To=".55"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Rectangle x:Name="hover" Fill="#FFBADDE9" Stroke="#FF6DBDD1" StrokeThickness="1" RadiusX="2" RadiusY="2" IsHitTestVisible="False" Opacity="0"/>
<ContentPresenter x:Name="content" Cursor="{TemplateBinding Cursor}" HorizontalAlignment="Left" Margin="{TemplateBinding Padding}" Content="{TemplateBinding Content}" ContentTemplate="{TemplateBinding ContentTemplate}"/>
</Grid>
</ControlTemplate>
</Button.Template>
</Button>
<Border Visibility="Collapsed" x:Name="ItemsHost" Grid.Column="1" Grid.Row="1" CornerRadius="1,4,8,4" BorderThickness="1,1,1,1" Padding="5,0,0,0" Margin="-27,0,0,0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
<Border.Background>
<SolidColorBrush Color="AntiqueWhite" />
</Border.Background>
<Border.BorderBrush>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FF0D0A45" Offset="0"/>
<GradientStop Color="#FF0D0A45" Offset="1"/>
<GradientStop Color="#FF38435B" Offset="0.2"/>
</LinearGradientBrush>
</Border.BorderBrush>
<Grid>
<Rectangle Fill="{x:Null}"
RadiusX="8" RadiusY="8"
VerticalAlignment="Bottom"
HorizontalAlignment="Right"
Width="100" Height="40"
Margin="0,0,3,3">
<Rectangle.Stroke>
<LinearGradientBrush EndPoint="1,1" StartPoint="0.7,0.7">
<GradientStop Color="#00FFFFFF" Offset="0"/>
<GradientStop Color="#7FFFFFFF" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Stroke>
</Rectangle>
<ItemsPresenter />
</Grid>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Notice the toggle button.
So then in the code behind you would do...
myDynamicTreeViewItem.Style = (Style)this.Resources["TreeViewContainerStyle"];

Resources