I am a little confused with wpf themes. I would like to have the wpf screens look the same on Vista, Windows 7 and Windows 8. So I have styled the components accordingly and they don't pose problems except when run on Windows 8. For example I have a combobox and I am changing its default background in xaml like this.
<Style TargetType="{x:Type ComboBox}" >
<Setter Property="FontStyle" Value="Normal"/>
<Setter Property="Height" Value="24" />
<Setter Property="Background" Value="{StaticResource GradientButtonBackgroundBrush}"/>
</Style>
The combobox Background property has no effect in windows 8 and all I get is a flat rectangle with a arrow on right (the default windows 8 combobox, which is rather poorly designed!).
So, my question is that how do I get the combobox look the same on all version of windows. I tried adding windows Aero theme in my App.xaml like below, but it has no effect on the combobox display. Here is how I added Aero theme
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/PresentationFramework.Aero;component/themes/aero.normalcolor.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
There is also another doubt regarding themes. I am building the wpf application on a windows 7 machine, which by default (I believe) has Aero Theme set. So, all my styles are based on the Aero theme when viewed on Windows 7 machine. What happens if I run the application on say XP. Then do I need to add an entry for the resource dictionary (Aero theme) in App.xaml as listed in code above?
I know my question is a bit vague, but believe me, I am really confused with default themes of wpf on different Windows versions.
EDIT: I still can't get combobox to style according to my needs. The combobox still appears like a gray rectangle.
Here is what I did. I downloaded the Aero.NormalColor.xaml from microsoft's site and included in themes folder of application. Then I added the following in App.xaml
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/Themes/Aero.NormalColor.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
Then I Compiled the application and deployed on Windows 8. Still the same combobox as was shown previously. Note that all other elements get styled properly according to the theme. I did the same with Luna.Metallic.xaml and every element gets styled except the ComboBox.
I believe that when I load a particular theme, which defines styles with ControlTemplate, then it should be picked by wpf. I am confused as to why only the ComboBox even after giving it a Aero (or Luna) Control Template doesn't change its appearance. Any ideas ?
EDIT-2 Screen shot of combobox appearance on Windows 8
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