Xubuntu - shortcut for magnifying screen [duplicate]

I started using Xubuntu a few weeks ago, and I'm annoyed with a strange behaviour : when I accidentally type a certain keyboard shortcut (yet to be determined), my screen shifts to a "magnified" mode (it gets a 10% zoom and starts to move the opposite way of my mouse pointer).

I'd like to know the shortcut (so I can at least leave this mode without disconnecting my session everytime...) and if possible, how to disable this completely. I found nothing related in the Keyboard manager.

Found the answer here The default shortcut is Alt + mouse wheel and it can be disabled in Window Manager Tweaks