Welcome to my userpage. This page isn't really all that interesting (but it's at least less embarassing than the last edit), nor does it have much of a point since I haven't done much serious editing on here in a long, long while, but you can browse here if you're so inclined. (to find a giant page full of userboxes, go here)
When this setting is activated, double-clicking anywhere on a page does the same thing as clicking on the edit this page tab. This only works with browsers that support Javascript (but all of the latest versions of all of the major browsers do).
To enable this feature click the Preferences link at the top of any page. Then click the Editing tab. Then check the box next to Edit pages on double click. And finally, click the Save button.
Note: After saving, you have to clear your browser's cache to see the changes. Mozilla/Safari: hold down Shift while clicking Reload (or press Ctrl-Shift-R), IE: press Ctrl-F5, Opera/Konqueror: press F5.