Sticky modifier keys in scenario editor

[CelticMinstrel]

Sometimes the game seems to miss an "option/alt" key release, which results in deleting the entity (item, etc) that you intended to edit.

[CelticMinstrel]

I've now experienced this in the game as well, after using Command-click to create a party and then trying to cast a spell after the scenario starts – instead of selecting a spell, click was opening the info dialog for the spell.

[NQNStudios]

What are the cases where someone would want to keep a modifier held down for a duration including multiple modified clicks?

Because, if there are not many or only a few, maybe we could have modified clicks clear the modifiers in lieu of the release event. (Hacky, weird, like the arrow key diagonals workaround.)

[CelticMinstrel]

The alt key is used to delete items from lists, so it would make sense to want to hold it down and click to delete several items. In other words, I don't think that works.

[NQNStudios]

I think for debugging these input-event related issues that can't be unit tested, it would be nice to add a simple debug overlay -- maybe it just shows an icon whenever a modifier key is pressed, and hides it when the release event happens. Then we can see if the visual feedback matches the behavior -- if it does, and we're sure we're only using event polling, we know we have an underlying SFML bug. If the visual doesn't match the behavior, then we're processing the events wrong.