This is unrelated to webui and should be handled by firefox extensions.

Why? Many web apps block this behavior because it's default for firefox. And what did you mean by firefox extensions?

This applies globally to firefox, not to web ui. What you need is a firefox extension that will disable this globally.

Not truth, it applies only for webui tab. E.g. photopea does the same. Look my patch, it just prevents default for alt

I think it's very nessasary patch because it breaks zooming with default alt key. It cancels after uping alt key

Can anyone else confirm this? For me, alt+mouse wheel works fine in Firefox 123.0.1 (64-bit).

Hm, maybe in windows it's disabled by default? Which variable have been set in about:config -> menuAccessKeyFocuses. I had this problem right after I started using the webui. And it appears on 2 devices

The key is true for me, but the menu is also always visible. The File menu gets focused when I release alt, but it does not interfere with zooming.

It because in your case there is no resize event

I can reproduce the problem now, after removing the menu, but disabling entire alt key because of just zoom is not right. Plus, wouldn't the code as it is now fail if you hold alt, press another key, release another key, then release alt?

disabling entire alt key because of just zoom is not right

I don't think so. I think it's okay to override browser's defaults for webapp

But it's your choice. How I can apply this event listner only for image box? Maybe add event lisner on targetElement instead of document

Plus, wouldn't the code as it is now fail if you hold alt, press another key, release another key, then release alt?

No, I tested it, and have retested it again. If I press something after alt, and then release alt, the menu isn't opened even on other pages

Made it, now alt is being suppressed only if the key in config is "Alt" and mouse was inside image

There is one problem, if you press alt outside image, then move mouse inside, and start zooming, menu will appear. But I think nobody presses alt before move mouse inside image

Is it not possible to check for e.code in the release event?

Yes, it can fix it. I forget about it. Pushed
keydown event is still needed for case alt was pressed inside zone, but released outside, what is a popular scenario