Problems with AltGr key with onboard

[Eberhard Beilharz]

If I click on the Alt-Gr key on a onboard keyboard, it sometimes takes some time until it updates the keyboard layout. After it updates, the AltGr key appears in red (locked), and the left Alt key also appears as pressed (gray). Because the left Alt key is also pressed it's not possible to enter any character from the AltGr layer.

It doesn't always happen and not with all keyboards, but if it happens with a keyboard it's pretty consistent. For example I observe it with the "English (US)" keyboard which has only has two characters on the AltGr layer, both on the extra '<' key to the left of 'z'.

(A separate issue is that I'm not able to get these characters with the AltGr key when using onboard, even when I unpress the left Alt key. With other keyboards I'm able to use this workaround to be able to type AltGr keys. And I don't have a hardware keyboard with that extra key, so I can't test if it's only an onboard or a general problem)

Expected behavior:
When I click on the AltGr key, the layout shows the characters of the AltGr-level and the AltGr key appears pressed (gray background).

Actual behavior:
When I click on the AltGr key, the layout shows the characters of the AltGr-level after a delay, the AltGr key appears locked (red background), and the left Alt key appears pressed (gray background).

$ lsb_release -rd
Description: Ubuntu 20.10
Release: 20.10

$ apt-cache policy onboard
onboard:
  Installed: 1.4.1-5
  Candidate: 1.4.1-5
  Version table:
 *** 1.4.1-5 500
        500 http://de.archive.ubuntu.com/ubuntu groovy/universe amd64 Packages
        100 /var/lib/dpkg/status

[Bushman (innerbushman)]

I had very similar behavior. The right AlrGr was locked (red) and left Alt was latched (gray).
No modifier was applied to the layout so I could not use my national letters (Polish) at all.
I tried everything in the settings window and nothing helped. Some settings even made it worse, to the point I couldn't get the right AltGr to latch. It would unlatch instantly (and no, I don't mean auto unlatch after n seconds, this was set to 0 - disabled).

Ultimately what I did was add second keyboard layout in system preferences, change to it and then change back to my national layout. This seems to have reset internals of onboard and everything started to work properly again.
If I encounter the same behavior again, I'll try to take note of circumstances in which it has manifested itself.

Onboard version: 1.4.1-7
OS: Manjaro