I do not know how I have just activated the (unwanted) feature. As I move the mouse, the screen is moving too all around. Is there a way of deactivating it? Unfortunately, it happens sometimes
Temporary Walkaround: I just turn-off the workstation and turn-on it again. The effect disappears. However, I would like to avoid this solution.
Solution found:
Attention: I was playing around with Ctrl and, thus, the trick does not work. The right key for this problem is Alt.
It seems that there is the same feature also in Ubuntu (based on Gnome). The answer comes from here.
To disable desktop zoom in XUbuntu, go
Settings
→Settings Editor
→xfwm4
→zoom_desktop
and uncheck it.