hmmm... I'm wondering if "shooting to non-unit" and "shooting to target without valid LoF" might be solved with the same hotkey?
perhaps the flashing error message could be adjusted to either
"no valid target - ctrl-click to force firing"
(this is an entirely new warning, of course)
or
"no LoF - ctrl-click to force firing"
?
by the way: would it be possible to draw a line between weapon and target while holding "ctrl"? I'm thinking of this as a kind of "sniper shot line-up" tool: by holding "ctrl", you can see the path a bullet would travel and identify obstacles (perhaps the line could even be green for valid LoF and red for blocked LoF?). by mouse-clicking while in this "sniper mode", the shot would be forced even if blocked... ?