CTRL key stuck when connecting from Linux to other system.

Hello!

Since Teamviewer 12, there has been this mission ciritcal problem: Once you press the AltGR on a German keyboard, Teamviewer thinks that CTRL was still pressed down eternally. Of course any GUI is unusable with CTRL pressed all the time. The only way for getting CTRL unstuck is to tell the remoe partner to press and release CTRL on the hardware keyboard.

Every fresh Linux installation I did within years suffered from the same problem,

This situation is unbearable, so please fix this. It can be so hard!?