Something

    def browse(self, event=None):
        """Event handler when browse button is pressed"""
        if self.type == 'save':
            filename = asksaveasfilename(parent=self, title=self.desc)
        elif self.type == 'load':
            filename = askopenfilename(parent=self, title=self.desc)
        elif self.type == 'dir':
            dirname = askdirectory(parent=self, title=self.desc)
        # Got a filename? Save it
        if self.type != 'dir':
            if filename:
                self.set(filename)
        else:
            if dirname:
                self.set(dirname)