AvalonEdit default style: since we specify an explicit background color, also specify the foreground color.

src/AddIns/DisplayBindings/AvalonEdit.AddIn/themes/generic.xaml

@@ -5,6 +5,7 @@
 	xmlns:core="http://icsharpcode.net/sharpdevelop/core"
 >
 	<Style TargetType="{x:Type local:SharpDevelopTextEditor}">
+		<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}" />
 		<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" />
 		<Setter Property="Template">
 			<Setter.Value>

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/TextEditor.xaml

@@ -4,6 +4,7 @@
 	xmlns:editing="clr-namespace:ICSharpCode.AvalonEdit.Editing"
 >
 	<Style TargetType="{x:Type AvalonEdit:TextEditor}">
+		<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}" />
 		<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" />
 		<Setter Property="FlowDirection" Value="LeftToRight"/> <!-- AvalonEdit does not support RTL, so ensure we use LTR by default -->
 		<Setter Property="Template">