in this case you even not need for special component. just use rendered attribute bound to some model boolean property. and manage this property in the button action.

B.t.w. do not forget that reRendering of conditionally rendered component is forbidden and should be performed by reRendering its parent (e.g. a4j:outputPanel)
Also the bean which kepts such properties should be session scoped.

For sure you could use togglePanel for that. Just define to facets empty and with required content and place corresponding toggleControl on the page.