Code:
/use flare
/click ActionButton1
That won't work either :P
It seems all mouse actions (hovering, clicking) with the interface is disabled when a 3D spell is targeting.
Even the virtual kind (SetBindingClick, /click).
Smells like they wanted to prevent people accidentally clicking the UI when targeting (I know I used to have this problem... until I setup a keybind for CAMERAORSELECTORMOVE).
Virtual clicks being disabled was probably an oversight, though :P