User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:67.0) Gecko/20100101 Firefox/67.0

Steps to reproduce:

Started Firefox under Wayland (sway wm 1.0 on Linux 5.1.8-arch1-1-ARCH):

$ GDK_BACKEND=wayland firefox

1. Navigated to www.youtube.com
2. Pressed Alt-Left

Actual results:

Nothing

Expected results:

Return back (as it does properly when run under Xwayland).

I can't reproduce this on nightly 20190619214046 in sway 00cffb (somewhere around sway 1.1-rc3). Alt keys work here.

It's indeed a Wayland issue but since I can't reproduce it on Wayland, I tried reproducing this on Nightly 69.0a1 (2019-06-20) (64-bit) , Ubuntu 18.04.2 LTS just to make sure this version wasn't affected. Alt keys work as expected.

This works now FF 71.0~b7+build1-0ubuntu0.19.10.1 (webrender and basic) and sway 1.2 / wlroots 0.8.1

I confirm this now works for me on Sway 1.2 + wlroots 0.8.1. FF 70.0.1 (64-bit, Arch Linux). I am using webrender and xinput2.

Also works for me on sway 1.4, firefox 76.

tjavdar: Can you try on an empty profile? Are you sure alt+arrows isn't bind to anything else in sway's config?

I'm also having this issue on GNOME Wayland with Firefox 81 from Debian unstable.

Actually left Alt works but right Alt does not.

Duplicate, was fixed in Firefox 68.

Hmm, this doesn't seem to be fixed in 78.7.0esr for me.

Can you try non-ESR? The fix was uplifted to 68 back then, but I have not tried ESR. My quick test now was in my usual nightly browser + sway/wlroots master, where alt keys still seem to work just fine.

I see what I was doing wrong, I was using the right-hand-side Alt key instead of the left-hand-side Alt key. The right-hand-side Alt key does not work for the shortcuts above (but the left one does), for both Firefox 85.0.1 and 78.7.0esr.

What keyboard layout are you using?

On a great deal of layouts, the key on the right is AltGr (and not Alt).
Both of these are entirely different keys with different usages.

English (US) according to GNOME settings.

Both keys work here. wev reports that they send Alt_L and Alt_R respectively, and both set Mod1. I'm using an ANSI keyboard with US layout.

Is wev reporting something else on your end?

wev doesn't work here. I'll retry after my next GNOME crash and or logout/reboot.

$ wev
wl_registry@2: error 0: invalid version for global wl_seat (17): have 5, wanted 6

I am not sure if xev is supposed to work under GNOME Wayland, but it prints this, I guess that is why my right-Alt isn't working.

KeyPress event, serial 34, synthetic NO, window 0x6a00001,
root 0x522, subw 0x0, time 718238613, (-659,577), root:(92,1020),
state 0x0, keycode 108 (keysym 0xfe03, ISO_Level3_Shift), same_screen YES,
XKeysymToKeycode returns keycode: 92
XLookupString gives 0 bytes:
XmbLookupString gives 0 bytes:
XFilterEvent returns: False

KeyRelease event, serial 37, synthetic NO, window 0x6a00001,
root 0x522, subw 0x0, time 718243028, (-659,577), root:(92,1020),
state 0x80, keycode 108 (keysym 0xfe03, ISO_Level3_Shift), same_screen YES,
XKeysymToKeycode returns keycode: 92
XLookupString gives 0 bytes:
XFilterEvent returns: False

Figured it out by searching for ISO_Level3_Shift, I had to change the "Alternate Characters Key" in the "Keyboard Shortcuts" of the GNOME Settings app.

I managed to disable the "Alternate Characters Key" by using this command-line:

gsettings set org.gnome.desktop.input-sources xkb-options '[]'

IIRC, ISO_Level3_Shift is a "technical name" for AltGr.
Most non English keyboard (and some English ones) actually have AltGr written on the right Alt.