Steps to reproduce:
1. Login using the HTML5 client in Chrome on Android
2. Open the virtual keyboard through the toolbar
3. Close the virtual keyboard through pressing the 'back'-button on the device
4. Tap anywhere in the ThinLinc session
This will open the virtual keyboard in addition to sending the click.
Does not happen in Firefox on Android nor in Chrome on iOS.
Could be related to bug 6007.
Still happens with latest trunk. Tested with Chrome 77.