Styling a custom windows phone 7 control - silverlight

Question

I'm using Microsoft Windows Phone 7 Tools Beta.
I have a custom control that lives in it's own project with the following code:
public class ValidationTextBox : TextBox
{
public ValidationTextBox()
{
DefaultStyleKey = typeof(ValidationTextBox);
}
}
Then my WP7 App contains the following style in the App.xaml
<Application.Resources>
<Style TargetType="my:ValidationTextBox">
<Setter Property="FontFamily" Value="{StaticResource PhoneFontFamilyNormal}"/>
<Setter Property="FontSize" Value="{StaticResource PhoneFontSizeMediumLarge}"/>
<Setter Property="Background" Value="Red"/>
<Setter Property="Foreground" Value="{StaticResource PhoneContrastForegroundBrush}"/>
<Setter Property="BorderBrush" Value="{StaticResource PhoneBorderBrush}"/>
<Setter Property="SelectionBackground" Value="{StaticResource PhoneAccentBrush}"/>
<Setter Property="SelectionForeground" Value="{StaticResource PhoneContrastBackgroundBrush}"/>
<Setter Property="CaretBrush" Value="{StaticResource PhoneTextCaretBrush}"/>
<Setter Property="BorderThickness" Value="{StaticResource PhoneBorderThickness}"/>
<Setter Property="Padding" Value="2"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="my:ValidationTextBox">
<Grid Background="Transparent">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver"/>
<VisualState x:Name="Disabled">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="EnabledBorder">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="DisabledOrReadonlyBorder">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="ReadOnly">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="EnabledBorder">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="DisabledOrReadonlyBorder">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="DisabledOrReadonlyBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneSubtleBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="DisabledOrReadonlyBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneSubtleBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="EnabledBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneContrastBackgroundBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="EnabledBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneContrastBackgroundBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="EnabledBorder" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Margin="{StaticResource PhoneTouchTargetOverhang}">
<ScrollViewer x:Name="ContentElement" BorderThickness="0" Margin="3,2" Padding="{TemplateBinding Padding}" Template="{StaticResource PhoneScrollViewerNoScrollBars}"/>
</Border>
<Border x:Name="DisabledOrReadonlyBorder" BorderBrush="{StaticResource PhoneDisabledBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="Transparent" Margin="{StaticResource PhoneTouchTargetOverhang}" Visibility="Collapsed">
<TextBox Background="Transparent" Foreground="{StaticResource PhoneDisabledBrush}" IsReadOnly="True" SelectionForeground="{TemplateBinding SelectionForeground}" SelectionBackground="{TemplateBinding SelectionBackground}" TextAlignment="{TemplateBinding TextAlignment}" TextWrapping="{TemplateBinding TextWrapping}" Text="{TemplateBinding Text}" Template="{StaticResource PhoneDisabledTextBoxTemplate}"/>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Application.Resources>
The XAML page that initiates the control initiates it as follows:
<my:ValidationTextBox InputScope="PersonalGivenName" Grid.Column="1" Grid.Row="0" x:Name="tbFirstName" Height="70" VerticalAlignment="Center" MaxLength="50" />
When I run the app, the control doesn't show up, it's blank.
What am I doing wrong?

Answer 1

You have two borders. The first contains a ScrollViewer that doesn't have any content. The second contains a TextBox which should show some content except that the border visibility is set to collapsed.

Answer 2

Have you tried giving Expressions Blend a go? It's a free download (part of the Windows Developer Tools which should be able to let you do all your styling work with a very nice GUI environment.
The second half of the Hello Phone lab in the Windows Phone 7 Training Kit runs through a few basic things you can do with Blend.