Draws a button

def draw_button(self, x, y, w, h, label):
        """Draws a button"""

        context = self.context

        self.draw_roundedrect(x, y, w, h)
        context.clip()

        # Set up the gradients
        gradient = cairo.LinearGradient(0, 0, 0, 1)
        gradient.add_color_stop_rgba(0, 0.5, 0.5, 0.5, 0.1)
        gradient.add_color_stop_rgba(1, 0.8, 0.8, 0.8, 0.9)
#        # Transform the coordinates so the width and height are both 1
#        # We save the current settings and restore them afterward
        context.save()
        context.scale(w, h)
        context.rectangle(0, 0, 1, 1)
        context.set_source_rgb(0, 0, 1)
        context.set_source(gradient)
        context.fill()
        context.restore()

        # Draw the button text
        # Center the text
        x_bearing, y_bearing, width, height, x_advance, y_advance = \
            context.text_extents(label)

        text_x = (w / 2.0)-(width / 2.0 + x_bearing)
        text_y = (h / 2.0)-(height / 2.0 + y_bearing) + 1

        # Draw the button text
        context.move_to(text_x, text_y)
        context.set_source_rgba(0, 0, 0, 1)
        context.show_text(label)

        # Draw the border of the button
        context.move_to(x, y)
        context.set_source_rgba(0, 0, 0, 1)
        self.draw_roundedrect(x, y, w, h)
        context.stroke()