[Affected versions]: Firefox 55.0a1 (2017-03-26) Firefox 54.0a2 (2017-03-26) Firefox 53.0b6 (20170323121323) [Affected platforms]: Ubuntu 16.04 32-bit [Steps to reproduce]: 1.Launch Firefox with clean profile. 2.Navigate to https://addons.mozilla.org/en-US/firefox/ 3.Choose an add-on and click on “+ Add to Firefox” green button. 4.Change the window position. 5.Click “Install” button. [Expected Results]: The add-on pop-up is displayed without any jerkiness or rendering issues. [Actual Results]: - The add-on pop-up is misplaced after changing the window position. - See the following screencast: https://www.dropbox.com/s/ei5k5nwzoafpwri/out-6-3.ogv?dl=0 [Additional Notes]: This issue is not reproducible on Windows 10 64-bit and Mac Os X 10.12.1 [Regression Range]: Last good revision: abecacadf9d3006029eb2208445521f495e80a70 First bad revision: 2e3bef583561c4812e6093a5ec639b1a58d0ab18 Pushlog: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=abecacadf9d3006029eb2208445521f495e80a70&tochange=2e3bef583561c4812e6093a5ec639b1a58d0ab18 I suspect that this issue was regressed by Bug 1201896.

Too late for a fix for 53, as we are heading into the last week of the beta 53 cycle and no one is assigned.

I think there's a dupe of this somewhere but I can't find it right now.