The onshow and onhide actions are used to control the visual effect of displaying and hiding a component.
<zk> <button label="Show Overlapped" onClick="win.doOverlapped();"/> <window id="win" border="normal" width="200px" mode="overlapped" action="onshow:anima.appear(#{self});onhide:anima.fade(#{self})" visible="false"> <caption image="/img/inet.png" label="Hi there!"/> <checkbox label="Hello, Effect!"/> </window> </zk>