1. Open test.zul in IE7
2. Set focus to minutes/seconds/am/pm fields
3. Click on "up/down" arrow to increment/decrement field value

The field value will get incremented/decremented the first time. However, the focus will move back to hour field, and subsequent clicking will increment/decrement the hour field.

<zk xmlns:h="native">
    <h:h1>ZK ${desktop.webApp.version}</h:h1>
    <timebox readonly="true" cols="12" format="medium" onCreate="self.value = new Date()"/>
</zk>