Closing of window kills whole app

I have a GTK# app which has several windows. All windows behave as expected, except for a single window which crashes the whole application when I close it. Now, the thing here is that this was the only window when I created the application, so in the beginning this 开发者_JAVA技巧was a feature. But, when I changed entry point, when another window became main window, I removed Application.Quit(); from offending window, but that doesn't stop him from killing the app. By looking at the code of the offending window, I can't figure out why the hell is it killing the whole app when it exits.

Any ideas?