backspace doesn't work in hex input

Steps to Reproduce

1. open the background color dropdown in the toolbar
2. focus on the hex input
3. press the backspace key

Current Result

nothing deleted

Expected Result

delete 1 character

Debug Information

• it's handled by keikai doKey() but doesn't propagate to a browser

Workaround

var exWidget = {};
zk.override(zss.Spreadsheet.prototype, exWidget, {
/* zk default afterKeyDown() prevent default and make backspace not working. Because spreadsheet widget also listener the backspace */
afterKeyDown_: function(event){
if (event.domEvent.target.nodeName == 'INPUT')

exWidget.afterKeyDown_.apply(this, arguments);
},
});