Create Region During Game Possible?

i was curious if it was possible to create a region during the game via triggers.

Regions as you know them are in fact what JASS calls rects. Either way, you can with JASS. GUI...is complicated. It doesn't differentiate properly.

if it's not too many lines of code can you show me a code in jass that creates a simple square centered at the position of a caster?


also, another question.. can these rects be labeled in some way so that an event can happen upon a unit entering it like it can with regions?

pseudo code:
- create region
- create rect
- add rect to region,
- register enter event for the region on a trigger of your choice
- remove rect
- save region in one variable so you can dispose it.
- eventually you'll have to destroy both the region and the trigger.

Something is telling me though, that you would prefer a unit in range event instead of all this nonsense,