Don't use the "Smooth Gesture" extension anymore!! It contains bad things (spyware)!! See here or here
Please remove it! Typ chrome://extensions in your address bar to see your installed extensions.
Howto Install and manage extensions. A better mouse extension is smartUp Gestures
A long time ago I have also installed this extension. However, I have discovered a few years later, that the extension contains a hidden spyware. At this time, the author of the extension had already withdrawn from the development. The extension was no longer offered from Google for installation. To my amazement, the domain (smoothgesturesapp.com) used at that time was no longer registered. So I bought it without further ado. After a few months I was able to determine from the logs that there were still several thousand extension installation worldwide. By chance I stumbled on an update function in the extension, with which I could create a rogue update and "distribute" it. So i can inform all the users about it :-). If you want to say thank you, click heremore info: