Gap between tab and top of window

There is a bug that is causing the tabs in FF to be the incorrect height when the FF window is initially opened. If the window is restored down and then maximized the issue goes away. I have verified by installing a fresh copy of FF and only installed Colorful Tabs to make 100% certain that it is Colorful Tabs causing this behavior.

- ColorfulTabs v4.8.1.6.4 or v5.1.1
- Firefox v5.0.1
- Windows 7 (64-bit)
- No installed themes (default)
- Only Colorful Tabs extension installed
- Install fresh copy of Firefox v5.0.1 (or FF Portable) and click the Maximize window gadget. Install Colorful Tabs v4.8.1.6.4 or v5.1.1 and restart FF. When FF opens there will be a two or three pixel high gap between the top of the tab and the top of the window - there should be no gap. Open at least more more tab and then click the Restore Down window gadget and then click the Maximize window gadget - the tabs will now be displayed properly with no gap between the top of the tab and the top of the window. Bare FF (w/no extensions) will never render a gap between the top of the tab and the top of the window. This behaviour makes it frustrating to switch between tabs because if you click the gap you're not hitting the tab.

Sorry about the screen shots. In retrospect I should have changed my window theme to a bright red or purple or something to make the gap more visible.