in the final version (I think they never worked in 4.x)
the icon attribute does not work.
Also in the current show case in my Firefox 4.0 the symbol is not shown.
As a workaround for me I use explicite iconLeaf, IconExpanded and IconCollapsed.
It is code duplication if you do not want to differ the symbols.
in RichFaces 4 attribute icon is no longer exists, you can use the following attributes instead: