This is what I have come up with for now...
I modified these Telerik source files:
Made a new color definition for "ControlBackground_Active
" and gave it a unique name, "ControlBackground_Active_Telestream
" so the change won't break anything else.
Commented-out the old "SelectionVisual" Border definition and replaced the Background value with the new color defintion.
<Border x:Name="SelectionVisual" Opacity="0"
Of course, I had to make a special build of the controls. My next question: Is there a way to do this by overriding these attributes frcm my application's XAML?