we still use richfaces 3.3.3 .
we are working on some user friendliy issues, so the user doesn't need to use the mouse.
one point is, when the user navigates with tab to a rich:comboBox the list of the combobox should popup on cursor down key.
this already happens when the user press back space to clear the value of the combobox . then the list pops up.
how to do the same on cursor down key?
onkeydown=" if ( event.keyCode== 40) document.getElementById('componentid').component.showList();"
solved my problem.