[BUG] Right Click Context menus not appearing correctly.

[Wskyy]

• OS: Windows 7 Pro, Intel I7-2670QM 2.20GHz RAM 12.0GB NVidia GT540M 1GB
• Version: 149.0.2 portable ( https://portableapps.com/apps/internet/r3dfox-portable )
• It occurred in the last version 148 too. This is a fresh install.

Describe the bug

The right click context menus are sometimes not appearing, will appear checkered, or won't click out. This happens both in the navigation bar and on websites. When the mouse is hovered over the menu items they rarely highlight. This doesn't happen on FF 115.

Also experiencing jerky video streaming that doesn't happen in FF115 but I guess that is another bug.

Additional context
Add any other context about the problem here.

I have a customized User Chrome file I have used for several years on FF115. I will upload it here in case it has anything to do with that. Probably has some entries I do not need.

userChrome.css

[the-r3dacted]

I wonder if it has to do with css changes. Because the fix that works for me did not work with e3k, the issue is practically solved on r3dfox with my fix (i can force the issue if I rapidly fiddle with menus and folders, but other than that it's basically gone), and r3dfox does a few extra changes to the menus.

The two reports of this issue with r3dfox since the fix both have custom css themes, so I wonder if removing the menu adjustments, or making them work around the issue (e3kskoy7wqk/Firefox-for-windows-7#142 (comment)) could work here.

[krystian3w]

Unless these are particularly severe hardware acceleration bugs, wrong background still stutters in the Classic/Basic themes for inactive items or when selecting “right” in the dropdown menu (as if the color of the letters were less important for recalculating something).

[Wskyy]

I wonder if it has to do with css changes.

Do you know how I could edit the css file so that it won't affect the right click menu? As you can see I love my clean and compact interface with tabs below the navigation and menu bars as they classically and appropriately were.

[the-r3dacted]

I'd try applying parts of your theme at a time, until you find what affects the menu.

Paste a chunk into userChrome.css, restart browser, check, paste more, restart browser, check, and so on.