HOW MANY TIMES DO YOU WROTE A LONG TEXT JUST TO REALIZE THAT WAS IN UPPERCASE AND MUST DELETE ENTIRELY TO REWRITE IN LOWERCASE? Well, no problemo...
This simple piece of code just let you do that: toggle upper and lower case with just one key press.
Personally I think it should come with the SO, a default action over the Caps Lock key when there is selected text.
It doesn't exist so I made it.