This is going to be a surprise to a number of people out there, but not only does the KDE Plasma desktop environment have gestures built in, but it has had them since the 3.2 (roughly) release. Gestures in KDE Plasma aren't just tied to the browser (I covered Firefox mouse gestues here), but pretty much anything in the desktop environment. With a few flicks of the mouse, you can make magic happen across your entire desktop experience. It all sounds new and exciting, but the functionality has been there for years and few people seem to know about this excellent feature. Let me tell you how it works.
To see existing mouse gestures that you can use, or create your own, fire up the KDE System Settings program. To do so, click the Application Launcher (the big K in the lower left, and select it from there; it's usually in the Favorites menu, or you can find it under the Computer section (or you can just type "system settings" in the search field of the launcher). When the System Settings window appears, click "Shortcuts and Gestures" which you'll find under the "Common Appearance and Behavior" section (see Figure 1).
Figure 1 : Mouse gesture configuration is found in KDE's System Settings.
First, make sure you enable gestures by clicking that text box in the top right section, then click apply (see close-up in Figure 2).
Figure 2 : Make sure you have enabled gestures as well. On a two-button wheel mouse, button 2 is the clickable wheel.
The Shortcuts and Gestures window has a sidebar to the left that offers three sets of shortcuts. These are custom shortcuts, standard application specific keyboard shortcuts, and global keyboard shortcuts. It doesn't specifically say "gestures" here because keyboard shortcuts are one type of shortcut while mouse gestures are another. Since the selection defaults to custom, and this is where we want to be, look at the middle section where you'll see "Input Actions settings" for a handful of applications, each label representing a group of applications with one of more shortcut (or gesture) defined below. To see the various predefined gestures, click the small arrow to the left of the label (see Figure 3).
Figure 3 : Every pre-defined gesture can be viewed, or changed.
Click on any action (e.g. Home under Konqueror Gestures) and a three-tabbed pane will appear to the left of the window. The tabs are labeled Comment, Trigger, and Action. The comment is exactly what it sounds like, a description of the shortcut with as little or as much information as you want. The trigger, in this case, is a mouse gesture. Using Home as our example, the gesture trigger is a stylized "h" that starts at the light green end of the line and ends at the dark blue. Click the Action tab and you'll see that it actually translates into the Konqueror "Ctrl+Home" keyboard shortcut which loads the home page.