Modifier keys not sent from OSK (Codeboard) #309

If you'd like to put out an incentive for fixing this bug, you can do so at https://issuehunt.io/r/bk138/multivnc?tab=idle

Is your bug report about the Desktop Multivnc or the Mobile MultiVNC?

• Desktop (wxWidgets) or Mobile (Android): Mobile

Which MultiVNC version are you using? 2.3.4

Which server are you connecting to?

• VNC server vendor: Qemu
• VNC server version: 10.0.11 (Debian 1:10.0.11+ds-0+deb13u1)
• OS version: FreeDOS 1.4
• OS language: unconfigured, default US English

Describe the bug
When Ctrl or Shift modifier keys are used in the Codeboard on-screen keyboard, MultiVNC ignores them, sending unmodified alpha keys instead.

It doesn't matter whether "QEMU Ext. Keys' is on or off.

To Reproduce

• Connect to Qemu VNC server running FreeDOS guest
• Start Watcom vi with a file
• On Codeboard, press Ctrl then d (vi: half-page scroll)
• Observe nothing happens
• Press Ctrl then d again
• Observe vi delete 1 line, expected behavior for pressing d twice without Ctrl
• Position cursor in middle of line.
• On Codeboard, press Shift then d (vi: delete to end of line)
• Observe nothing happens
• Press Shift then d again
• Observe vi delete 1 line, expected behavior for pressing d twice without Shift
• Exit vi
• Start Freemacs
• On Codeboard, press Ctrl then x (common emacs control prefix)
• Observe literal x inserted, expected behavior for pressing x without Ctrl. It is at this point impossible to exit Freemacs, a different VNC viewer must be used.

Expected Behavior

Ctrl then d on on-screen keyboards should send Ctrl-d. Ctrl then x should send Ctrl-x. Shift then d should send Shift-d. Etc.

AVNC has expected behavior with the same server and guest.

Screenshots

For the Desktop Version (please complete the following information):

• OS and version:
• Xorg version used:
• Wayland version used:

For the Mobile Version (please complete the following information):

• Android version: 11
• Installed from Play Store, F-Droid, Amazon Appstore: I'm really not sure if it was Play Store or F-Droid. It's been a long time since I installed it.

Additional context

I'll try other OSKs later, and reply