I pressed something around my mouse pad (keys in the altgr region+mousepad - quite possibly multitouch) and suddenly the whole X11 display zoomed around 10%. That means I can see 90% of the 1920x1080 screen in a somewhat blurry version. When I move the cursor, the 90% follows the cursor, so by panning around I can see everything on the screen. Since it applies to everything my guess is that it is caused by xfwm or Xorg.
If I suspend the machine, it seems to go away in the lock screen, but when the lock screen is unlocked, the blurriness and zoom re-appears. Taking a screenshot grabs what is displayed on my screen (i.e. the 90% but scaled to 1920x1080).
I can see the usefulness of this in certain situations, but I would really like to exit it (other than rebooting).
I use xfce on Linux Mint.