Very easy. Looking back on the Vertex theme, the JS could be much cleaned up as I have grown as a developer but here is the simple fix.
In jquery_bits.js find:
$("ul.topnav li span").click(function() { //When trigger is clicked...
//Following events are applied to the subnav itself (moving subnav up and down)
$(this).parent().find("ul.subnav").slideDown('fast').show(); //Drop down the subnav on click
$(this).parent().hover(function() {
}, function(){
$(this).parent().find("ul.subnav").slideUp('slow', "easeInQuint"); //When the mouse hovers out of the subnav, move it back up
});
//Following events are applied to the trigger (Hover events for the trigger)
}).hover(function() {
$(this).addClass("subhover"); //On hover over, add class "subhover"
}, function(){ //On Hover Out
$(this).removeClass("subhover"); //On hover out, remove class "subhover"
});
Replace with:
$("ul.topnav li").mouseover(function() { //When trigger is clicked...
//Following events are applied to the subnav itself (moving subnav up and down)
$(this).find("ul.subnav").slideDown('fast').show(); //Drop down the subnav on click
$(this).hover(function() {
}, function(){
$(this).find("ul.subnav").slideUp('slow', "easeInQuint"); //When the mouse hovers out of the subnav, move it back up
});
//Following events are applied to the trigger (Hover events for the trigger)
}).hover(function() {
$(this).addClass("subhover"); //On hover over, add class "subhover"
}, function() { //On Hover Out
$(this).removeClass("subhover"); //On hover out, remove class "subhover"
});