If you wish to trigger the drop down menu without clicking it, you could do so by trying the following steps:

1. Access Confluence Administration Page
2. Navigate to Custom HTML

3. Insert the following string to "At end of the HEAD" fields 

   <script>
   AJS.toInit(function(){
     AJS.$('.ajs-menu-bar > li.ajs-menu-item').hover(
       function(){ 
         AJS.$(this).children('a')[0].click();
       },
       function(){ 
         AJS.$(this).children('a')[0].click();
         AJS.$(this).removeClass('hover');
       } 
     );
   });
   </script>

4. Save

Note : This above script is not applicable for Confluence running higher than v6.14 hence use the below script for higher versions:

<script>
AJS.toInit(function(){
  AJS.$('.aui-header-primary > .aui-nav > li:first, .aui-header-secondary > .aui-nav > li:nth-child(2), .aui-header-secondary > .aui-nav > li:nth-child(3), .aui-header-secondary > .aui-nav > li:nth-child(5)').hover(
    function(){ 
      AJS.$(this).children('.aui-dropdown2-trigger')[0].click();
    },
    function(){ 
      AJS.$(this).children('.aui-dropdown2-trigger')[0].click();
    } 
  );
});
</script>

Source : Answers thread Answered by David Simpson