wpf ContentPresenter wont enable/disable

Question

Hi,

I've overridden a ComboBox in order to add an extra button at the end of the combo - i'm using this to help navigate round my application.

Its a M-V-VM App that has an Edit-Save/Cancel mechanism that disables or enables the controls depending on whether or not the user is in 'edit mode'. I wanted my navigation button to always be available whether the View is enabled or disabled.

To achieve this I'm binding the ToggleButton and the ContentPresenter to a IsEditable property on my Model.

The toggle button enables and disables as expected but the Text of the combo stays enabled.

As the text is delivered by the ContentPresenter and the ContentPresenter has an IsEnabled property I can't understand why it wont disable?

Can anyone assist? Thanks Andy

<Style TargetType="local:EntityCombo">
    <Setter Property="SnapsToDevicePixels" Value="true"/>
    <Setter Property="OverridesDefaultStyle" Value="true"/>
    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
    <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
    <Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
    <Setter Property="MinWidth" Value="120"/>
    <Setter Property="MinHeight" Value="20"/>
    <Setter Property="FontSize" Value="12" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:EntityCombo" >
                <Grid>
                    <ToggleButton 
                        IsEnabled="{Binding IsEditable}"
                        Name="ToggleButton" 
                        Template="{DynamicResource ComboBoxToggleButton}" 
                        Grid.Column="2" 
                        Focusable="false"
                        IsChecked="{Binding Path=IsDropDownOpen,Mode=TwoWay,RelativeSource={RelativeSource TemplatedParent}}"
                        ClickMode="Press">
                    </ToggleButton>
                    <Button Grid.Column="2" Style="{DynamicResource EntitySelectedButton}" Command="{TemplateBinding EntitySelected}" CommandParameter="{TemplateBinding SelectedItem}"></Button>
                    <ContentPresenter
                        IsEnabled="{Binding IsEditable}"
                        Name="ContentSite"
                        IsHitTestVisible="False" 
                        Content="{TemplateBinding SelectionBoxItem}"
                        ContentTemplate="{DynamicResource SelectionBoxItem}" 
                        ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
                        Margin="3,3,23,3"
                        VerticalAlignment="Center"
                        HorizontalAlignment="Left" />
                    <Popup 
                        Name="Popup"
                        Placement="Bottom"
                        IsOpen="{TemplateBinding IsDropDownOpen}"
                        AllowsTransparency="True" 
                        Focusable="False"
                        PopupAnimation="Slide">
                        <Grid 
          Name="DropDown"
          SnapsToDevicePixels="True"                
          MinWidth="{TemplateBinding ActualWidth}"
          MaxHeight="{TemplateBinding MaxDropDownHeight}">
                            <Border 
            x:Name="DropDownBorder"
            Background="{StaticResource WindowBackgroundBrush}"
            BorderThickness="1"
            BorderBrush="{StaticResource SolidBorderBrush}"/>
                            <ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True">
                                <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
                            </ScrollViewer>
                        </Grid>
                    </Popup>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="HasItems" Value="false">
                        <Setter TargetName="DropDownBorder" Property="MinHeight" Value="95"/>
                    </Trigger>
                    <Trigger Property="IsEnabled" Value="false">
                        <Setter Property="Foreground" Value="DarkGray"/>
                    </Trigger>

                    <Trigger Property="IsEnabled" Value="true">
                        <Setter Property="Foreground" Value="Red"/>

                    </Trigger>
                    <Trigger Property="IsGrouping" Value="true">
                        <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
                    </Trigger>
                    <Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="true">
                        <Setter TargetName="DropDownBorder" Property="CornerRadius" Value="4"/>
                        <Setter TargetName="DropDownBorder" Property="Margin" Value="0,2,0,0"/>
                    </Trigger>

                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Style.Triggers>
    </Style.Triggers>
</Style>

Answer 1

This is a tricky one, but I've been knee-deep in WPF long enough to be very persistent. :) After suggesting this in my last comment my insanity drove me to test it out and it is indeed the problem:

The template sets ComboBox.Foreground based on ComboBox.IsEnabled, but you want to style the content based on DataContext.IsEnabled, so you would need to style the ContentPresenter itself. But you cannot style ContentPresenter because it inherits from FrameworkElement, not Control. But you can replace the ContentPresenter with a ContentControl and style it with the appropriate triggers for your disabled appearance.