User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:64.0) Gecko/20100101 Firefox/64.0 Build ID: 20180915115425 Steps to reproduce: Note: After Bug 1490742, gfx.webrender.all.qualified is enabled by default. 1. Install and Launch OBS Studio. (https://obsproject.com/) 2. Open Firefox. 3. On the preview window for OBS, Right-click and select Add > Window Capture. 4. Click OK. 5. Open the Window dropdown and select [firefox.exe] <Window title>. Actual results: The window capture in OBS displays as a white box. Expected results: The window capture in OBS displays the rendered content in Firefox.

Thank you! :) It's only a problem with ANGLE.

mozregression --good 2018-01-15 --bad 2018-05-01 --pref gfx.webrender.all:true > 5:29.24 INFO: Last good revision: edfd9ffbd7208ef0a59f40a0d77d8dd53c905cb9 > 5:29.24 INFO: First bad revision: d328d8eda8e68d669ebc77184c8d8d870cafcb7c > 5:29.24 INFO: Pushlog: > https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=edfd9ffbd7208ef0a59f40a0d77d8dd53c905cb9&tochange=d328d8eda8e68d669ebc77184c8d8d870cafcb7c > d328d8eda8e6 sotaro — Bug 1191971 part 2 - Add capatiblity to enable DComp r=bas > 19142efa84a5 sotaro — Bug 1191971 part 1 - Create child window in gpu process r=bas

Does capture work with Edge or Chrome?

Oh, legit. Sorry. It would be only a Firefox regression. It doesn't work with IE11, Edge and Chrome Dev 71. Chrome users are advised to disable hardware acceleration. So this could be even a wontfix?

Even if you wanted to remove other graphics backends some day, it would be enough to temporarily disable gfx.webrender.dcomp-win.enabled for such a window capture.

Likewise, chrome.exe --disable-direct-composition is mentioned as a solution.

"Not a bug"