My sub-factories are often not squared, contain other stuff or the mod window simply gets too crowded based on a single rectangular area. This could be nicely enhanced by allowing to multiple selections:
- if a new box is drawn while holding shift the new box is added to the current selection
- if a new box is drawn while holding ctrl the new box is subtracted from the current selection
- drawing a new box without any modifier key pressed replaces the current selection as before
