Apparently, the unwanted popping up of the virtual keyboard is a recurrent problem in Ubuntu without generic solution. Today, I suddenly had it too, on a desktop computer without anything like a touch screen. Yesterday evening, I received a load of updates and also installed the VLC player. So I cannot tell what caused it.
There is an option switch among the accessibility settings, but while this can enable the OSK, it cannot suppress it when it appears for causes only known to itself.
It has been suggested to remove caribou, onboard and ibus. The first two are not found installed by apt (Zorin 17.2) and the latter doesn't solve the issue.
There are extensions such as block-caribou that are version dependent and I have not found one that was accepted by gnome (and possibly they aren't maintained this far).
But this is the Zorin Forum, and in this case it was a Zorin issue that got me. It is easily remedied once you have found where to look, so hopefully it may help others:
- make sure gnome-extensions is installed (in a terminal:
sudo apt install gnome-shell-extensions
) - open 'Extensions' from the activities/Zorin/start menu
- scroll down to 'Zorin Screen Keyboard Button' and switch it off.
good luck.