Found this issue on Windows platform, using Nightly, build ID: 20140410030200 I'm currently using two different monitors, one of 22" and a smaller one, 17". If enough tabs are pinned, the minimise, restore down and close button will overlap the tabbar. Steps To Reproduce: 1. Open Firefox on the bigger display (maximized window). 2. Open about 40 tabs. 3. Pin at least 35 of them. 4. Restore down Firefox and move it to the smaller display. 5. Maximize it. Expected result: Firefox is maximized and correctly displayed. Actual result: The minimise, restore down and close buttons overlap the tabbar. Notes: - this also reproduces on Mac OS X and Ubuntu platforms. - reproduced on latest Aurora, build ID: 20140410004003 - reproduced on Fx 29 beta 7, build ID: 20140410150427

I'm not sure how we could actually fix this, and on the other hand, I also wonder who would really get into this state realistically, so marking P5.