I'm using Mozilla Firefox 107.0.1 on linux, using latest Gnome.

I get a hang sometimes that doesn't cause a crash, and force me into force-quitting Firefox and restarting it, that I don't know how to debug more. It seems to be somewhat intermittent, but it's easy to trigger so I can reproduce it with ease by triggering the initial conditions. It's unclear whether all the conditions are necessary, but here are the ones with which I can reproduce with almost 80% reproducibility:

• have two Firefox windows open (I've got two displays, and I put one window on each display; not sure it matters)
• one of these windows plays a video from Google Drive
• the other has Slack open

I can trigger the hang by double-clicking any text in the Slack window. The video keeps on playing in the background (I can hear the sound), but Firefox's UI as a whole is frozen.

$ uname -r
Linux karch 6.0.11-arch1-1 #1 SMP PREEMPT_DYNAMIC Fri, 02 Dec 2022 17:25:31 +0000 x86_64 GNU/Linux

I've attached gdb to Firefox after a hang, on the main/parent process most likely:

#0  0x00007fb2d0fb46f0 in  () at /usr/lib/libc.so.6
#1  0x00007fb2d0fbac12 in pthread_mutex_lock () at /usr/lib/libc.so.6
#2  0x00007fb2cf1a287f in  () at /usr/lib/libX11.so.6
#3  0x00007fb2cf1c1986 in _XReadEvents () at /usr/lib/libX11.so.6
#4  0x00007fb2cf1a656b in XIfEvent () at /usr/lib/libX11.so.6
#5  0x00007fb2d03335c3 in gdk_x11_get_server_time () at /usr/lib/libgdk-3.so.0
#6  0x00007fb2cfd6f496 in  () at /usr/lib/libgtk-3.so.0
#7  0x00007fb2cfd6f74e in  () at /usr/lib/libgtk-3.so.0
#8  0x00007fb2cfd696e6 in gtk_clipboard_set_with_data () at /usr/lib/libgtk-3.so.0
#9  0x00007fb2c9a787d3 in  () at /usr/lib/firefox/libxul.so
#10 0x00007fb2c97c6061 in  () at /usr/lib/firefox/libxul.so
#11 0x00007fb2c6c48c15 in  () at /usr/lib/firefox/libxul.so
#12 0x00007fb2c734a1b3 in  () at /usr/lib/firefox/libxul.so
#13 0x00007fb2c5f80dfc in  () at /usr/lib/firefox/libxul.so
#14 0x00007fb2c5f7ec72 in  () at /usr/lib/firefox/libxul.so
#15 0x00007fb2c5f78c52 in  () at /usr/lib/firefox/libxul.so
#16 0x00007fb2c5f76b9f in  () at /usr/lib/firefox/libxul.so
#17 0x00007fb2c6eb69f1 in  () at /usr/lib/firefox/libxul.so
#18 0x00007fb2c789156d in  () at /usr/lib/firefox/libxul.so
#19 0x00007fb2c7599425 in  () at /usr/lib/firefox/libxul.so
#20 0x00007fb2c655def1 in  () at /usr/lib/firefox/libxul.so
#21 0x00007fb2c655c590 in  () at /usr/lib/firefox/libxul.so
#22 0x00007fb2c655b6bd in  () at /usr/lib/firefox/libxul.so
#23 0x000055dedfc8d1dc in  ()
#24 0x00007fb2d0f54290 in  () at /usr/lib/libc.so.6
#25 0x00007fb2d0f5434a in __libc_start_main () at /usr/lib/libc.so.6
#26 0x000055dedfc9d0e5 in _start ()

Let me know if I can help with more information!