targeting a specific object? like wall/floor/object? you'd either need more than one hotkey for that, or something to toggle through the options... maybe a hotkey and then mousewheel to select the actual object? this might become complicated easily.
I have just come up with another idea here: https://openxcom.org/forum/index.php/topic,1012.0.html
maybe we can even come up with a kind of advanced sniper mode, where you can target specific voxels? first select a tile, then select the exact voxel with mouse (x/y axis) and mousewheel (z axis)?
I think the two thread are becoming redundant.
in any case the force fire should be a simple implementation no need to create a new button or a combination of keys, as i posted in the other thread.
I think a simple notification should be displayed
"no LoF, double-click to force fire"
Also this could be in the in the option menu to show or not show the notification.
This simply says are you sure you want to attempt to fire even if you probably won't hit there target since there are obstacles
This way experienced user can simply use the feature and do not have to be bugged about it.
or in the first instance of the notification have a little tick mark.
"[ ] Show only on first time"
or
"[ ] Always show notification"