Webaccess Android to Linux VM: AltGr combinations don't work (mostly)

ThinLinc
,
1

When accessing the XFCE-desktop of a linux VM from android via webaccess using a physical keyboard, AltGr-combinations don’t work but only in one single application (FeatherPad - a QT based application). So I am not able to input for example @, €, µ.

Accessing the same VM using android/samsung’s onscreen keyboard or from a linux client via webaccess works flawlessly.

The following screenshots show the events fired when pressing AltGr-Q using

Unbenannt 1
Unbenannt 11920×2485 196 KB

Environment:

  • Android device / physical keyboard: Samsung Galaxy Tab S9 / Samsung book cover keyboard slim, german layout (alternatively used: fintie bluetooth keyboard)
  • Browsers used: firefox, chrome
  • VM qemu Host/Guest: Ubuntu / MX Linux; same behaviour with ubuntu as guest

Thanks in advance for any help

Thomas

2

We have the same device here, and I can confirm I’m seeing the same thing here.

Unfortunately, it seems to be a bug in the browsers or the system. They are reporting a normal Alt to Web Access, rather than an AltGr. So that is what we send to the ThinLinc server.

We have reported the issue to the browsers here:

https://bugs.chromium.org/p/chromium/issues/detail?id=1021856

Unfortunately, there hasn’t been any activity. :confused:

We’re tracking this issue with regard to ThinLinc here, if you want to be notified of updates:

https://bugzilla.cendio.com/show_bug.cgi?id=7431

3

Could it be that firefox and chrome report at the same time AltGr and the Alt modifier to Web Access, see my screenshots?

I now have found the following workaround for getting characters from the 3rd level:

  • Press and hold AltGr
  • Press and release (left) Alt
  • Press desired key, e.g. “Q” for @ or “E” for € on germany keyboard layout
  • Release AltGr

So perhaps there is a possibility for web access/novnc to deal with this behaviour by ignoring/resetting the alt modifier flag when altgr is pressed?

4

No, they just report the Alt. The extra AltGr is generated on the server, since it sees that AltGr needs to be pressed for a @. So it temporarily fakes an AltGr press.

That does indeed happen to work. :slight_smile:
Unfortunately, it relies on a bug, so it’s not really a viable path forward…

That could in theory be done, but on the server instead of the client. But it might break things for other users. The server doesn’t know that the Alt was really an AltGr, so it cannot just ignore it. If it did, then pressing Alt and another key would break randomly, depending on the client and server keyboard layout.

5

I see. Thank you for the information and your help!