[Tracking Requested - why for this release]: Visual regression since 45 Build identifier: https://hg.mozilla.org/releases/mozilla-aurora/rev/20d95004d8d18062255a9b4afa37b447b282a248 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0 ID:20160118004007 When I test Bug 1240680, I found a rendering glitch. Reproduced on Nightly46.0a1 and Aurora45.0a2 with/without HWA. Reproducible: not always, but easy reproducible. Once happens, it seems persists. STR: 1. Load https://vimeo.com/ and logged in 2. Scroll down to the video thumbnails. 3. Quickly mouse over icons(hart, clock and paper airplane) Actual Results: Background blue color does not render properly See attached screenshot Expected Results: Background blue color render properly Regression window: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=097cac1912b9658ba68389b5dd72d4cc45e762d5&tochange=21cabf6ab3e9a254cdc9370986f300213b346cb2 Via local build, Last Good: b0a00d6915bb First Bad: 21cabf6ab3e9 Regressed by: 21cabf6ab3e9 Markus Stange — Bug 1201327 - Don't repaint the whole frame subtree when background-position changes. r=dbaron

Reproduced on Ubuntu.

Tracking as it is a visual regression on a major website

They're changing background-position on a button element, so this is the same as bug 1227327.

Tracking this in the duplicated bug where I will note that this also affects vimeo.