User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:57.0) Gecko/20100101 Firefox/57.0 Build ID: 20170829100404 Steps to reproduce: 1. Use Firefox Nightly with a bunch of opened tabs. 2. Switch to / login as another operating system user without logging off. 3. switch back users and try to interact with Firefox Actual results: Content is not responding to clicks. Switching tabs is also not possible. Quitting Firefox, reopening it and restoring the session makes it work again. Expected results: It should be interactive, just like before switching users.

Please troubleshoot with Safe Mode: https://support.mozilla.org/kb/troubleshoot-firefox-issues-using-safe-mode

I tried to reproduce it step-by-step, but it worked this time. Some time later I had the problem again. Maybe it is caused by a specific action done by the second OS-user. Anyways, if I find out more accurate steps to reproduce it reliably, I'll post them here. thanks

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:57.0) Gecko/20100101 Firefox/57.0 Firefox: 57.0a1, Build ID: 20170831100404 I have tested this issue on latest Nightly build, and could not reproduce it. When you find a more accurate STR please post them. Thank you

I have exactly the same issue as this, and it seems to be fairly consistent, across two different computers. Disabling plugins or running in Safe Mode have no effect : firefox will still be unresponsive when switching back. I am currently running OSX 10.14 (Mojave), but this also occurred on previous versions. It has also been consistent between Firefox versions. I am currently running Version 63.0 (64-bit) To reproduce: 1. Run Firefox 2. Switch to another user 3. Log out and log back in to the original user (or switch back). 4. Firefox will be unresponsive : cannot switch tabs, scroll, click or select menu items. Sometimes it is possible to wait, and Firefox will become responsive again : however I timed it a few times, and it was between 20 and 50 seconds before it became responsive again, with a visible refresh on the screen when the browser became responsive. However sometimes Firefox has to be closed and restarted before it will work normally again. When unresponsive, if the window is scrolled or a tab closed by clicked in the correct spot, nothing will change. However, switching to a diferent application and then back to firefox will show that the window has scrolled (or the tab closed). It's not a major headache, but it is definitely an issue which I have consistently seen over the last few months.

This looks like a duplicate of https://bugzilla.mozilla.org/show_bug.cgi?id=1422855

Closing as duplicate of bug 1422855.