- if you use a bookmark bar, its font colour changes when you open another window.
It is originally white, then it turns dark blue.
See the screenshots:


It happens regardless of how you open another window: it doesn't matter whether you just run another instance of the program, open another window from within (e.g. Ctrl+N shortcut) or tear one of the tabs off.
Basically, the font is always white on window #1, but navy blue on #2, #3 etc.
I tried to test different themes, and as far as I can tell, this occurs on everyone of them (although it's much easier to notice on the dark ones, obviously).
I haven't checked if Google Chrome does the same thing, because I don't really want to install it.
My OS = Windows XP Professional / SP3