That does appear to do the trick. I was trying to use it with EVENT_RETICLE_TARGET_CHANGED to check for a blacklisted target and then hide it with that, but it only half works. Sometimes it fails to disable it or it's extremely slow to re-enable it on something not blacklisted.
You probably recall what request it was for, but:
http://www.esoui.com/downloads/info1623-NoInteract.html
Am I going about it the wrong way?