Append GPL license before Stallman gets mad at me
Add a behaviour to ToolButtons (open, save...)

ToolButtons now have an implemented behaviour. This means that
they will actually do something when you press them.

* New Document button now will create a blank new document when
  you press it. If the current document has been edited, it will
  ask you to save it first.

* Open Document button will now open an existing document when
  you press it. Again, if the current document is dirty, it will
  ask you to save it first.

* Save Document button will save a document into a location.
  If it's a new file that hasn't been saved yet, it will ask for
  a location.

Care was taken when adding the logic code to make the message
dialogs safe. They shouldn't glich, they shouldn't save when you
don't want to save and they should save when you want to.