A JavaScript custom event is fired if a
<tc:panel/> is collapsed or expanded.
tobago.panel.show is fired before the panel is expanded.
tobago.panel.shown is fired after the panel is expanded. (Does not wait for a possible Ajax reload.)
tobago.panel.hide is fired before the panel is collapsed.
tobago.panel.hidden is fired after the panel is collapsed. (Does not wait for a possible Ajax reload.)