Steps to Reproduce

1. load the zul
2. use mouse to hover on the first menuitem
3. press down key twice

Current Result

2 menu selection highlight box appear

Expected Result

just 1 selection highlight appears

Debug Information

• 2 highlights
  1. .z-menuitem-content:hover
  produces the highlight box for the mouse hovering over a menu item.
  2. .z-menuitem-hover>.z-menuitem-content
  produces the highlight box for keyboard selection.