Closed issue by thamesynne on void-packages repository

https://github.com/void-linux/void-packages/issues/31933

Description:
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### System

* xuname:  Void 5.11.22_1 x86_64-musl GenuineIntel notuptodate rFF
* package:  firefox-89.0.2_1             (but has been observed since at least Firefox 88)
* X server: Xvnc provided by tigervnc-1.10.1_3

### Expected behavior

Not the actual behaviour...

### Actual behavior

When right clicking to bring up a context menu, or dropping down a selection box, occasionally Firefox will spawn a new process, which doesn't do anything useful but does block at least Firefox, and sometimes the entire X server. Manually killing this process unfreezes everything, allowing the session to continue.

No error output appears from Firefox to suggest what's gone wrong.

Other than the fact that it results from Firefox dropping down a menu, I can see no pattern to why it occurs. Sometimes it happens with every 3rd or 4th right click, sometimes an entire session will pass without it happening.

I have greated a 32-bit glibc chroot and tested Firefox-i686 in that environment; the bug does not seem present there. Has Firefox grown an incompatibility with musl?

### Steps to reproduce the behavior

Bug is intermittent - see above.

(I apologise for not being able to provide more detail.)