When you drag scroll in starcraft 2 sometimes whole screen jumps to a location opposite mouse position.
How to reproduce (shown in drag scroll bug demo):
I move mouse up and down just a little and press drag scroll hotkey often (which is spacebar in my keymap). Notice that it performs drag operation and sometimes screen jumps randomly to a location opposite to a mouse pointer. Also notice that sometimes pointer jumps to a center of screen for a moment.
This bug makes game nervous to play, as it produces unexpected results.
It exists from WoL, was reportet several times, breaks gameplay but still is not patched.