WPF Setting the colour of the ComboBox down arrow button

Question

I am trying to style a WPF ComboBox so that it matches a black-theme that is being considered for our next project.

My problem is that if the ComboBox's background is black, the button doesn't show up (since it is also black).

For some reason I have not been able to find any information about how to change it's colour.

The following XAML is that I currently have for styling the ComboBox in black:

<ComboBox Name="myComboBox" VerticalAlignment="Top" Width="120"  HorizontalAlignment="Right">
    <ComboBox.Resources>
        <LinearGradientBrush  x:Key="{x:Static SystemColors.HighlightBrushKey}"  StartPoint="0,0" EndPoint="0,1">
            <GradientStop Color="#FFCBCBCB" Offset="0.0"/>
            <GradientStop Color="#FF7C7C7C" Offset="0.3"/>
            <GradientStop Color="black" Offset="1"></GradientStop>
        </LinearGradientBrush>
    </ComboBox.Resources>
    <ComboBox.Background>
        <LinearGradientBrush StartPoint="0,0" EndPoint="0,0.5">
            <GradientStop Color="white" Offset="0"/>
            <GradientStop Color="black" Offset="1"/>
        </LinearGradientBrush>
    </ComboBox.Background>
    <ComboBoxItem Name="cbi1">Item1</ComboBoxItem>
    <ComboBoxItem  Name="cbi2">Item2</ComboBoxItem>
    <ComboBoxItem Name="cbi3">Item3</ComboBoxItem>
</ComboBox>

Any help on the topic would be greatly appreciated.

Thanks,

-Frinny

Answer 1

You are going to have to modify the ControlTemplate for the ComboBox.

The control itself is surprisingly-at-first-but-not-when-you-think-about-it complex. I would recommend going into Blend (if you have it) and extracting the ControlTemplate. Otherwise, you can get the XAML for a ComboBox using XAMLWriter.

This unfortunately named page (I don't think this is really "Kid's Stuff", do you?) has an example of doing both of these things.