You could also do below in a common.js file which would be included in all jsp's.
This way no need to write anything extra (oncompletetopics) for individual selectboxes :-
$(document).ready(function() {
$("select").each( function (){
var sel = this;
// setting tool tip of select box as selected value
var index=sel.selectedIndex;
if(
sel.id!=""){
$('#'+
sel.id).attr('title',sel.options[index].text);
}
// setting tool tip for showing on hover
for(i=0;i<sel.length;i++){
sel.options[i].title = sel.options[i].text;
}
}
);
});