When I'm playing a hero with cloak like Nova, it takes a few seconds of not engaging in combat before I can cloak again. During this time, I frequently find my hero happily shooting up any minions or structures that are nearby, resetting the cloak timer. Most of the time, this isn't what I want to have happen.

I heard that the S key is supposed to cancel all actions, but I haven't had success with this. I've sat uncloaked next to minions fighting minions while I spam the S key and Nova still shoots nearby enemies. Many times moving around helps, but on occasion I find myself on a stealth mission in the enemy base and am unable to move without drawing fire from forts and towers.

How can I prevent my uncloaked hero from unloading on everything red in sight?