You can partially fix this by modifying some code in the file /tcl/pull-down-menu-defs.tcl. Inside proc_doc ad_pdm, search for the phrase "cascade.addMember". It should put you in the 'if' statement that writes the javascript for each menu entry. Replace the entire if statement (there should be 3 branches) with the code below:
# modified on 8/17/00 - Kevin Cheng
# append statements were replaced to output the correct javascript.
if {[empty_string_p $parent_label]} {
append script "
$c_parent_label.cascade.addMember("$label","$url",false);"
} elseif {$number_of_children > 0} {
append script "
var $js_label = new NavBarItem("${label} ...","$url",true);"
} else {
append script "
var $parent_label = new NavBarItem("$label","$url",false);"
}
# Note that I did NOT test this on menus more than 2 levels deep, but it works with the default admin pull-down-menus. (they're pretty cool!).