This is a quick hack to work around Chrome's current bug in the Selection API where if you hold-down left click to select, and try to right-click to copy, without letting go of the left mouse button, you will lose your selection.
Note that this bug only occurs when the block of text is large enough to overflow and generate a scrollbar. It actually has to display a scrollbar.
So, I obviously tried to write this JavaScript in a way that will not impact frequent events firing, so I'm sorry if the absurdly C-like code looks awful.