I've now checked with xkbev which key codes is received. On the local keyboard AltGr produces keycode 108. When connected via ofreerdp the same key on the remote keyboard produces 2 keycodes - 37 and 64. Which probably is Ctrl and Alt. And this does not work. There are more differences but this one is the biggest problem.
Connecting the Linux box from Win10 instead OS/2 the Win AltGr produces keypress 37, keyrelease 37, keypress 113 and keyrelease 113.
So either our ofreerdp should send
1) keypress 108 when pressing AltGr and keyrelease 108 when releasing AltGr (in the meantime the other keys are should sent as usual) to mimik local behaviour or
2) keypress 37, keyrelase 37, keypress 113, keyrelease 113 to mimik Win behaviour. But Win make autorepeat of this sequence as long as AltGr is pressed. So option 1) like local keyboard maybe better
Have to say I'm no expert on this. But working combinations are -
- Win to Linux
- OS/2 to Win
non AltGr working is with -
- OS/2 to Linux
Also /kbd: options seems to do nothing (not implemented?) on our OS/2 client (ofreerdp.exe) as it always shows the usage messages. But this can be overcome with xrdp.ini and xrdp_keyboard.ini entries (force DE with override instead default to EN).