Reproducible on: Nightly 36.0a1 (2014-11-11) *intermittently*. Affected platform(s): Windows 7 64-bit. STR: 1. Make sure you have aero enabled in Windows 7. 2. Launch Firefox with a clean profile. 3. Click menu → Customize → click Title Bar from the bottom of the palette → click Exit Customize. 4. Press F11 to enter full screen. 5. Press ctrl + w to exit Firefox. 6. Launch Firefox again and press F11 to exit full screen. 7. Resize the browser window both horizontally and vertically. Expected result: The UI of the browser is displayed properly, including the Title Bar, Tab Strip, various toolbar buttons, etc. Actual result: After resizing the window, the tab strip displays a black gradient as background, the tab themselves are not affected. Additional notes: - I was unable to reproduce this issue on Windows 8 or Windows 8.1 at all, so this might be aero-related. Firefox 34 Beta 8 (build1 / 20141110195804) and Aurora 35.0a2 (2014-11-11) are *not affected*. - A regression range for this bug could not be determined due to its intermittent nature. - Screenshot depicting the issue: http://i.imgur.com/C6oIlfd.png. - about:support details of the testing machine used to replicate it: http://pastebin.mozilla.org/7267743. - It's also worth mentioning that this might be something related or similar to Bug 951646.
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