def handle_colorstop_changed(self, config_widget):
if config_widget.valid:
reordered = sorted(self.stop_vbox.get_children(), key=lambda cs: cs.get_offset())
gradient = Gradient()
for i, cs_config in enumerate(reordered):
self.stop_vbox.reorder_child(cs_config, i)
offset, color = cs_config.get_colorstop()
if color is not None:
gradient.add_colorstop(offset, color)
self.option.value = gradient
self.preview.set_gradient(gradient)
self.emit('changed')
