Show a Colour Chooser dialog
        
        Usage: C{dialog.choose_colour(title="Select Colour")}
        
        @param title: window title for the dialog
        @return: a tuple containing the exit code and colour
        @rtype: C{DialogData(int, str)}

def choose_colour(self, title="Select Colour", **kwargs):
        """
        Show a Colour Chooser dialog
        
        Usage: C{dialog.choose_colour(title="Select Colour")}
        
        @param title: window title for the dialog
        @return: a tuple containing the exit code and colour
        @rtype: C{DialogData(int, str)}
        """
        return_data = self._run_kdialog(title, ["--getcolor"], kwargs)
        if return_data.successful:
            return DialogData(return_data.return_code, ColourData.from_html(return_data.data))
        else:
            return DialogData(return_data.return_code, None)