where to cut half doors

i am about to cut my half doors and was wondering why most people leave the part on where the window would shut on the top. Is this needed to stay on there so that the door doesn't fold up or what?

I think it's a personal preference. I'm going to leave mine because I think it looks better when the door is shut because your door seal isn't exposed.

It also gives you the opportunity to fabricate some type of cover later if you decide to do that.