I’ve added the ability to highlight tabs with different colors from Tabs Studio context menu:

Highlighting colors in Tabs Studio context menu
If you use just one color (still accessible with Ctrl+Click), but want to change it, the custom style is slightly different now (note the new
HighlightIndex property):
<Style TargetType="TabsStudio:TabInternals" BasedOn="{StaticResource DefaultTabInternalsStyle}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=(TabsStudioMarker:Properties.HighlightIndex),
RelativeSource={RelativeSource AncestorType=TabsStudio:Tab}}" Value="1">
<Setter Property="Background">
<Setter.Value>
<LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
<GradientStop Color="Transparent" Offset="0.9"/>
<GradientStop Color="Green" Offset="0.9"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
</DataTrigger>
</Style.Triggers>
</Style>
In this Marker update I’ve also removed a small gradient transition in underline, fixed occasional loss of first tab highlighting after loading a solution in VS 2010, slightly changed highlight commands placement in the context menu.
Download link: Marker v1.0.4.