Make an option under file to chose which project you are closing.
I love being able to open multiple projects but I regularly close the wrong project by accident.
It would be nice to have the choice of which project you are closing under the "close project" option in the "File menu"
Right now you are pretty much guessing, hoping and praying you have the project selected when you select close project but you don't know which you are closing for certain. Having a a submenu pop out and list all open projects would be a simple and clean solution.