All pages in the same desktop could be accessed in an event listener. For the current page of a component, you could use the getPage method in the org.zkoss.zk.ui.Component interface.

To get a reference to another page, you first have to assign an identifier to the page being looked for.

<?page id="another"?>
...

Then, you could use the getPage method in the org.zkoss.zk.ui.Desktop interface as follows.

<zscript>
    Page another = self.getDesktop().getPage("another");    
</zscript>