This might be a problem with the RR buttons rather than the tab control, however it's probably something that needs sorting out.
I'm using a tab control on a form. On that tab control I'm using RR buttons to present another popup form.
When that form closes the RR buttons are not being redrawn - the tab is "empty" where the button should be.
Moving the mouse over the button causes it to appear.
Looks to me as though there are some WM_PAINT messages missing. A call to InvalidateRect() required perhaps?
Andrew