make sure any editor is removed when calling discardEditor for the main window controller, as abortEditing does not properly call the delegate methods
make sure any editor is removed when calling discardEditor for the main window controller, as abortEditing does not properly call the delegate methods

JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim