STR:

1. Go to about:addons.
2. Set page zoom to 120%.
3. Click an extension panel menu.

The extension cards are rendered over the panel menu.

Adding some z-index to the panel-list element should fix it.

I would like to work on it, can I take this up?

You're welcome to work on this, I just tried the z-index approach I suggested and it doesn't appear to be working as I expected. Perhaps there's some other element it could work on, but this also seems like it could be a bug with zooming.

I think this was fixed by the changes to the panel in bug 1525175.

I can still reproduce it on latest Nightly at zoom levels 150% and larger.

Ah, got better since you need to zoom to 150% I guess but I can see it too.

I can't reproduce this at any zoom level on MacOS anymore.

@Kestrel, Are you still seeing this? And if so on which platform?

I can still reproduce this at 150% zoom with latest Nightly 75.0a1 (2020-02-28) on Ubuntu 19.10. It is more likely to occur if you click the page background first before clicking the menu button. With the menu still open, if you move the cursor outside the addon card so that it loses its hover border, the menu will no longer be obstructed.

My test result, FF 73.0.1 stable and 74.0b7 dev on Windows 20H1:
Normal: 110, 120, 123, 130, 133, 150
Has this issue: 140, 143, 153, 160, 163, 170

Thanks. I'm not seeing this on my regular Nightly but can confirm it's still happening at some zoom sizes on my local build. Trying to sort out if it's a platform issue since setting a z-index doesn't seem to fix it and it's intermittent for me.