GDJSZLYT73DLC2YKPWUSXCIC6HW3YMHFGQXU66FLHVMRNMI5UCLQC
-- If any applicable button handler returns true, it'll propagate the click to other handlers.
--
-- Buttons can nest in principle, though I haven't actually used that yet.
--
-- Don't rely on the order in which handlers are run. Within any widget, all
-- applicable button handlers will run. If _any_ of them returns true, the
-- event will continue to propagate elsewhere in the widget.