steps to reproduce

1. run the zul with IE11 and 8.0.3.FL.20160701-Eval

   	<menubar>
   	    <menu label="First Menu">
   	        <menupopup>
   	            <menuitem label="SOME OTHER ITEM" />
   	            <menuitem label="some item" />
   	        </menupopup>
   	    </menu>
   	    <menu label="2nd menu">
   	        <menupopup>
   	            <menuitem label="SOME OTHER ITEM" />
   	            <menuitem label="some item" />
   	        </menupopup>
   	    </menu>
   	</menubar>
   

2. click the "First Menu"

result

debug info

• chrome and firefox doesn't have this bug.