Disabled Combobutton should not be able to focus or controlled by keyboard

Steps to Reproduce

https://zkfiddle.org/sample/16iabs/2-keyboard-disabled-combobutton

Current Result

disabled combobutton is accessible by keyboard

Expected Result

disabled combobutton should not be accessible by keyboard

Debug Information

tabindex="0" will be add to dom no matter it's disabled or not

Workaround