Tab into timebox prevents from typing the hours and minutes correctly

When you tab into the component from another input box, you cannot type the hours and minutes correctly

<zk>

<intbox id="item1" />

Timebox: <timebox id="tb" cols="14" format="HH:mm" onCreate="self.value = new Date()" mold="rounded"/>

<checkbox label="Use rounded timebox" checked="true"

onCheck='tb.mold=self.checked? "rounded": "default"'/>

</zk>