I have a problem with Firefox Beta 52. It doesn't happen on Firefox ESR 45. Sometimes when I try to drag tab, it doesn't move. It happens unpredictably, however, I noticed one specific scenario when it happens 1. Open https://mozdevs.github.io/MediaRecorder-examples/record-live-audio.html , allow to use the microphone 2. Install https://addons.mozilla.org/en-US/firefox/addon/devedition-theme-enabler/ , enable developer theme 3. Place mouse directly above the microphone favicon in the tab, hold left mouse button, move mouse horizontally Result: Tab doesn't move Expected: Tab should move

I see an issue when drag the webrtcIndicator (Firefox icon) above tabs bar, the moving / focus is sometimes paused. on Fx52.0 & Fx53.0b1, with/without DevEdition theme. Also occurred in Fx45.8.0esr. I did not see the problem when dragging tab with "allow to use the microphone", and don't understand the "microphone favicon in the tab".

Is it clear from attached screenshot what "microphone favicon in the tab" meant? If you don't like the wording, please suggest a better description Can you reproduce this regression now?

Only appear when the tab is in background.

I'm dragging tab, not sharing icon. Mozregression-gui generated this regression range: https://hg.mozilla.org/integration/fx-team/pushloghtml?fromchange=ee2eba8cdedda9ec12caa8aa4903a525df1aaf2f&tochange=e077a9ed54589316850312a6c4460ef15472109d -> 1275262 – implement device sharing animation on background tabs https://bugzilla.mozilla.org/show_bug.cgi?id=1275262

I can only reproduce when using the compact theme. Dão, do you happen to know if the compact theme does something different related to dragging tabs?

(In reply to Florian Quèze [:florian] [:flo] from comment #5) > I can only reproduce when using the compact theme. Dão, do you happen to > know if the compact theme does something different related to dragging tabs? http://searchfox.org/mozilla-central/rev/624d25b2980cf5f83452b040e6d664460f9b7ec5/browser/themes/shared/compacttheme.inc.css#275-279

(In reply to Dão Gottwald [::dao] from comment #6) > (In reply to Florian Quèze [:florian] [:flo] from comment #5) > > I can only reproduce when using the compact theme. Dão, do you happen to > > know if the compact theme does something different related to dragging tabs? > > http://searchfox.org/mozilla-central/rev/ > 624d25b2980cf5f83452b040e6d664460f9b7ec5/browser/themes/shared/compacttheme. > inc.css#275-279 I guess based on this that we'd need to reset pointer-events to none for the sharing icon or something? The same might be true for other things which shouldn't be draggable.