One thing pisses me off to no end: When you drag a window and accidentally make a small "left-right-left" movement, everything on your screen is minimized to the tray. There is no button to restore this.
You can actually just grab the same window and make a corresponding "up-down-up" movement and it'll bring everything back. On personal machines I turn it off but if I'm doing something for someone else, this is a good thing to know.
The fact that it's defaulted to on and surprises users who don't even know about it is the problem.
"Minimize all other windows except this one" is a function that is rarely used and definitely not something a small movement of the mouse should trigger.
One thing pisses me off to no end: When you drag a window and accidentally make a small "left-right-left" movement, everything on your screen is minimized to the tray. There is no button to restore this.
f*cking retarded features.