Sending AltGr to tigervnc from xrdp

[Matt Burt]

xrdp developer here. tigervnc is used as the default back end on rpm-based systems.

I've got a user posting an issue with AltGr on a Spanish keyboard:-

https://github.com/neutrinolabs/xrdp/issues/3292

I'm tracing this through, and we're sending tigervnc a 0xffea KeySym for the AltGr key. This is however ending up mapped to the ALT_L key and hence the keyboard is not working correctly.

I've now discovered the long history of problems with this key and VNC in general (I had no idea). I'm guessing in this case we're falling foul of one of the heuristics used to work out when this key is actually being pressed.

My question is; "with a TigerVNC server, what is the best way to send AltGr"? Is it Ctrl_L+Alt_R? If so, I can simply add an option to do this - most of our users are using tigervnc anyway.

[Matt Burt]

Nevermind - it seems I'm an idiot. If I send XK_ISO_Level3_Shift rather than XK_ALT_R, all is well.

Sorry about the noise.