KDE has built in support for mouse gestures enabling you to greatly increase your productivity by just drawing thing with your mouse on the screen. You can configure gestures under
Shortcuts and Gestures,
Custom Shortcuts, then check the
Gestures checkbox. The gestures you define can execute commands, call D-Bus API calls or emulate key presses.
Example: launching applications
You could for instance draw a plus-sign gesture with your mouse to activate