Loading a project when a project is already loaded causes a crash

[WiggleWizard]

Load a project, then go to File -> Open. Open a different project

[antopilo]

Maybe this could be prevented by forcing to go back to the project browser, it would also reduce the visual clutter of the File menu.

Adding something like -> Quit to project launcher

[WiggleWizard]

I think naming it "Close Project..." might be a bit less confusing an less ambiguous to the user perhaps. The ellipse would dictate that a dialog will follow.