When two or more tabs rows exist and you select tab in the top row this row goes to the bottom. Standard behavior, but confusing nevertheless. Not anymore! The rows are not affected by selection now:
Selected tab in the top row
Interesting side effect of this change is that when tab is selected and mouse is over it, tab’s background is a mix of white and blue colors on Vista:
Mouse over the selected tab
Standard behavior is a white tab’s background in this case, but I don’t know yet how to achieve this with controls library I use. Accidental mix of white and blue colors is interesting, so I’m leaving it as it is for now.
Tabs Studio Blog (organizing Visual Studio document tabs) 
Awesome… I have been waiting for this. Well done
Comment by SurfRat — May 7, 2009 @ 12:50 pm