Active screen edges allow you to activate effects by pushing your mouse cursor against the edge of the screen. Here you can configure which effect will get activated on each edge and corner of the screen.
Click with any mouse button onto a square and select an effect in the context menu. Edges with a blue square have already an attached effect, a grey colored square indicates that no effect is selected for this edge.
The number of accessible items in the context menu depends on the settings in the module Desktop Effects in the Workspace category. Select your favorite effects on the from the Window Management group. This activates the corresponding items in the context menu.
If you are looking for the setting to enable switching of desktops by pushing your mouse cursor against the edge of the screen choose one of the Present Windows effects from the context menu.
In the Window Management section you can enable to Maximize windows by dragging them to the top of the screen or to Tile windows by dragging them to the side of the window and set a percentage of the screen to trigger the tiling.
In the Other Settings section configure if you want to switch to another desktop when pushing the mouse cursor to an edge of the screen, e.g. only when moving windows.
Activation delay is the amount of time required for the mouse cursor to be pushed against the edge of the screen before the action is triggered.
Reactivation delay is the amount of time required after triggering an action until the next trigger can occur.