Pressing right Control key in a virtual desktop as first keypress locks the control key on.

Steps to reproduce:

- create a new virtual desktop from Windows
- open a terminal inside the virtual desktop
- give focus to Windows on local, outside of the NoMachine virtual desktop
- press Alt-Tab or click in the NoMachine virtual desktop to give it focus
- press the right Control key
- type in the terminal: the control key is locked in the ON position

As a workaround:
- give focus to Windows on local
- give focus back to the NoMachine virtual desktop
- press any key other than right control: typing is now normal.

Notes:
- this doesn't occur when pressing the left Control key as first key press
- problem doesn't affect custom sessions.