Prompts the user for the filepath to save and then saves the image.

def accept(self):
        """
        Prompts the user for the filepath to save and then saves the image.
        """
        filetypes = 'PNG Files (*.png);;JPG Files (*.jpg);;All Files (*.*)'
        filename = QFileDialog.getSaveFileName(None,
                                               'Save Snapshot',
                                               self.filepath(),
                                               filetypes)
        
        if type(filename) == tuple:
            filename = filename[0]
        
        filename = nativestring(filename)
        if not filename:
            self.reject()
        else:
            self.setFilepath(filename)
            self.save()