Steps to Reproduce

<zk>
  <zscript>
    ListModelList model = new ListModelList();
    model.add("abc");
    model.add("bcd");
  </zscript>
  <searchbox model="${model}"/>
</zk>

select a value, try to unselect it

Current Result

mouse controls are a bit non intuitive (has to click the element again to unselect it)
no keyboard shortcut

Expected Result

"X" icon to clear the current value
clear when pressing the delete/backspace key (when the box is focussed, not open)

Debug Information

Workaround

http://zkfiddle.org/sample/165gk5i/1-workaround-clear-searchbox-model