The Accidental Overview
Ubuntu’s default desktop environment, GNOME, utilizes a feature known as “Hot Corners.” By design, if you forcefully push your mouse cursor into the extreme top-left corner of your screen, the desktop will instantly zoom out, activating the Activities Overview. This reveals all your open windows, your workspaces, and the search bar. While this gesture is a fast way to multitask for some, it is a constant source of frustration for others. If you are simply trying to click the “File” menu in a maximized application or aiming for the close button, slightly overshooting the target will trigger the jarring zoom animation, completely breaking your concentration.
Disabling the Corner Trigger
To prevent these accidental disruptions and completely disable the Hot Corners gesture (stopping the Activities Overview from launching on mouse hover), you must adjust the GNOME multitasking settings.
In recent versions of Ubuntu, this setting is easily accessible via the main graphical interface. Click the cluster of icons in the top-right corner of your screen and click the gear icon to open the Settings app. In the left-hand navigation sidebar, scroll down and click on Multitasking. Look at the very top of the right-hand panel for the “General” section. You will see a toggle switch explicitly labelled Hot Corner, accompanied by the description “Open the Activities overview when the cursor goes to the top left corner.” Click this toggle switch so it turns grey (Off). The change takes effect immediately. You can now violently throw your mouse into the top-left corner, and your screen will remain perfectly still, allowing you to click menus with precision.