The airport editor works just fine and doesn't do what you are reporting: I can edit a jetway just fine, and pressing the Reset button does what is supposed to do and it doesn't close or reopen.
Are you maybe running the editor in Full screen mode ? If yes, best to use Windowed mode while editing. And, it's very difficult to help you if you don't give any details about your configuration, like which simulator you use, which scenery are you editing, etc.
