Do you want to turn off all feedback? Set SimpleDropSink.EnableFeedback to false...
How are you setting the Foreground color? Is during an CellFormat event?
Not really a design error -- more of a limit on what can be expressed in the language....
It seems to be fixed for me. Can you still reproduce?
Header resize background flicker
Unable to reproduce
clicking +/- button to expand/collapse doesn't always work
Unable to reproduce.