WPF Change Button style for mouse over and pressed - wpf

Question

I want to change the default color of the button for IsMouseOver and IsPressed, but something is wrong with my code. It's not applying, buttons still have their default style.
This is my code:
<Style x:Key="PanelButtonStyle" TargetType="Button" BasedOn="{StaticResource {x:Type Button}}">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="False">
<Setter Property="Background" Value="Purple" />
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Background" Value="#479DE0"/>
</Trigger>
</Style.Triggers>
</Style>
And on the button...
<Button Style="{StaticResource PanelButtonStyle}" .../>

Answer 1

The IsMouseOver and IsPressed brushes are hardcoded into the default ControlTemplate for the Button.
You could copy the default template into your XAML markup by right-clicking on the Button element in design mode in Visual Studio or in Blend and choose Edit Template->Edit a Copy.
You would then edit the template as per your requirements:
<Style x:Key="PanelButtonStyle" TargetType="Button" BasedOn="{StaticResource {x:Type Button}}">
<Style.Resources>
<Style x:Key="FocusVisual">
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate>
<Rectangle Margin="2" SnapsToDevicePixels="true" Stroke="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" StrokeThickness="1" StrokeDashArray="1 2"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<SolidColorBrush x:Key="Button.MouseOver.Background" Color="#479DE0"/>
<SolidColorBrush x:Key="Button.MouseOver.Border" Color="#FF3C7FB1"/>
<SolidColorBrush x:Key="Button.Pressed.Background" Color="#FFC4E5F6"/>
<SolidColorBrush x:Key="Button.Pressed.Border" Color="#FF2C628B"/>
<SolidColorBrush x:Key="Button.Disabled.Background" Color="#FFF4F4F4"/>
<SolidColorBrush x:Key="Button.Disabled.Border" Color="#FFADB2B5"/>
<SolidColorBrush x:Key="Button.Disabled.Foreground" Color="#FF838383"/>
</Style.Resources>
<Setter Property="Background" Value="Purple" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Border x:Name="border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="true">
<ContentPresenter x:Name="contentPresenter" Focusable="False" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsDefaulted" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="Background" TargetName="border" Value="{StaticResource Button.MouseOver.Background}"/>
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource Button.MouseOver.Border}"/>
</Trigger>
<Trigger Property="IsPressed" Value="true">
<Setter Property="Background" TargetName="border" Value="{StaticResource Button.Pressed.Background}"/>
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource Button.Pressed.Border}"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Background" TargetName="border" Value="{StaticResource Button.Disabled.Background}"/>
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource Button.Disabled.Border}"/>
<Setter Property="TextElement.Foreground" TargetName="contentPresenter" Value="{StaticResource Button.Disabled.Foreground}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Just adding triggers to the Style without modifying the template won't work because of how the default template is defined.

Answer 2

Button has already triggers to change the visual state defined internally.
You have to override the default template to override the default triggers (See: Styles and templates):
<Style x:Key="PanelButtonStyle" TargetType="Button" BasedOn="{StaticResource {x:Type Button}}">
<Setter Property="Background" Value="Purple" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Button">
<Border BorderThickness="{TemplateBinding BorderThickness}"
BorderBrush="{TemplateBinding BorderBrush}"
Background="{TemplateBinding Background}">
<ContentPresenter />
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Background" Value="#479DE0"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>