your gonna need to be more specific then that!

are you asking how to check if the item your dropping has been dragged outside the menu window?
Then yes, you could simply do a position check when you drop your item.
If it's outside the window then it will return a boolean to that specific item and handle it accordingly. (i.e. remove the item from an array in the menu)

But thats just one way to do it, it all depends on the menu your making and the effect you want to achieve

I would go for distance rather than rect. you might be intersecting two or more possible drop targets.

Just take the distance from current drag location at the time of release to the potential drop targets, and snap to the closest target if it beats the threshold check. if it doesn't, it snaps back to where it came from.