The <ace:panelStack> component utilizes its own component handler such that the children of the <ace:stackPane> are not included in the server-side component tree. In the example below, the size of the component tree is first shown as per regular JSF server-side rendering. Toggle facelet value to true for all panes, and see the size of the component tree reduce as content is only included for the selected stackPane in the <ace:panelStack>.