Dude, the worst BY FAR is when (while on a laptop), you're typing, and the side of your left palm (beneath your thumb) just touches the touchpad, which of course functions as a left-click, and if the mouse cursor is out of the typing field (where I always move it so it doesn't distract me while typing), then because a left-click was received, the cursor moves out of the typing field and "focuses" on the rest of the firefox window, so a) everything I type after doesn't get recorded and b) if I hit backspace, then that's the firefox shortcut for "back", so back it goes, and when I hit forward to return to where I was, everything I had been typing has vanished
(as I'm sure will come as little surprise given the specific nature of my description, this has happened to me on far too many occasions
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