Bug introduced in V10.1 or earlier and persisting through V11.3
Print is triggered just by pressing the mouse button.
EventHandler[Framed[1], {"MouseDragged" :> (Print@RandomReal[])}]
Documentation claims something else:
"MouseDragged" mouse moving with primary button depressed
Bug confirmed by WRI
f@RolfMertig_ := RolfMertig^n
? (I kinda feel more comfortable with thef[...]
notation, myself). $\endgroup$ – Daniel Lichtblau Jan 28 '15 at 0:38