This demo shows how data is populated in a tree using MVC and EL. (DefaultTreeModel)
The tree supports the display of rows of data, similar to a listbox or grid but with the concept of data hierarchy.

<groupbox id="grp" closable="false" mold='3d' apply="demo.tree.tree_model.BinaryPackageController">
	<caption label="ZK Binary Package" />
	<tree id="tree" hflex="1" model="${grp$composer.treeModel}">
		<treecols>
			<treecol hflex="1" label="Path" />
			<treecol hflex="1" label="Description" />
			<treecol width="100px" label="Size" />
		</treecols>
		<template name="model">
	        <treeitem>
	            <treerow>
	                <treecell label="${each.data.path}"/>
	                <treecell label="${each.data.description}"/>
	                <treecell label="${each.data.size}"/>
	            </treerow>
	        </treeitem>
    </template>
	</tree>
</groupbox>

package demo.tree.tree_model;

import org.zkoss.zk.ui.Component;
import org.zkoss.zk.ui.select.SelectorComposer;
import org.zkoss.zul.DefaultTreeModel;

import demo.data.PackageDataUtil;
import demo.data.pojo.PackageData;

public class BinaryPackageController extends SelectorComposer<Component> {

	private static final long serialVersionUID = 43014628867656917L;
	
	public DefaultTreeModel<PackageData> getTreeModel() {
		return new DefaultTreeModel<>(PackageDataUtil.getPackageData());
	}
}

package demo.data;

import demo.data.pojo.PackageData;
import org.zkoss.zul.DefaultTreeNode;

public class PackageDataUtil {

    public static DefaultTreeNode<PackageData> getPackageData() {
        return newNode(null,
                newNode(new PackageData("/doc", "Release Notes and License")),
                newNode(new PackageData("/dist", null),
                        newNode(new PackageData("/lib", null),
                                newNode(new PackageData("/zkforge", null),
                                        newNode(new PackageData("ckez.jar", "CKeditor", "1709KB")),
                                        newNode(new PackageData("timelinez.jar", "Timeline", "283KB")),
                                        newNode(new PackageData("timeplotz.jar", "Timeplot", "112KB")),
                                        newNode(new PackageData("gmapsz.jar", "Google Maps", "95KB")),
                                        newNode(new PackageData("zuljsp.jar", "JSP", "129KB"))
                                ),
                                newNode(new PackageData("/ext", null),
                                        newNode(new PackageData("commons-fileupload.jar", "Upload Features")),
                                        newNode(new PackageData("commons-io.jar", "Upload Features")),
                                        newNode(new PackageData("jcommon.jar", "Chart Component")),
                                        newNode(new PackageData("jfreechar.jar", "Chart Component")),
                                        newNode(new PackageData("jasperreports.jar", "Jasperreport related Component")),
                                        newNode(new PackageData("itext.jarjxl.jar", "Jasperreport related Component")),
                                        newNode(new PackageData("poi.jar", "Jasperreport related Component")),
                                        newNode(new PackageData("commons-collections.jar", "Jasperreport related Component")),
                                        newNode(new PackageData("commons-logging.jar", "Jasperreport related Component")),
                                        newNode(new PackageData("commons-digester.jar", "Jasperreport related Component")),
                                        newNode(new PackageData("bsh.jar", "Scripting in Java interpreter for zscript (BeanShell)")),
                                        newNode(new PackageData("js.jar", "Scripting in JavaScript (Rhino)")),
                                        newNode(new PackageData("groovy.jar", "Scripting in Groovy")),
                                        newNode(new PackageData("jruby.jar", "Scripting in Ruby (JRuby)")),
                                        newNode(new PackageData("jython.jar", "Scripting in Python (Jython)")),
                                        newNode(new PackageData("Filters.jar", "Captcha Component.")),
                                        newNode(new PackageData("mvel.jar", "Evaluate the expressions (MVEL)")),
                                        newNode(new PackageData("ognl.jar", "Evaluate the expressions (OGNL)"))
                                ),
                                newNode(new PackageData("zcommon.jar", "ZK Core Jar File", "413KB")),
                                newNode(new PackageData("zcommon-el.jar", "ZK Core Jar File", "100KB")),
                                newNode(new PackageData("zel.jar", "ZK Core Jar File", "151KB")),
                                newNode(new PackageData("zhtml.jar", "ZK Core Jar File", "57KB")),
                                newNode(new PackageData("zml", "ZK Core Jar File", "57KB")),
                                newNode(new PackageData("zk.jar", "ZK Core Jar File", "1056KB")),
                                newNode(new PackageData("zkbind.jar", "ZK Core Jar File", "270KB")),
                                newNode(new PackageData("zkplus.jar", "ZK Core Jar File", "122KB")),
                                newNode(new PackageData("zul.jar", "ZK Core Jar File", "1311KB")),
                                newNode(new PackageData("zweb.jar", "ZK Core Jar File", "196KB"))
                        ),
                        newNode(new PackageData("/src", "Jar Format Source Code")),
                        newNode(new PackageData("/xsd", "XSD files for Development")),
                        newNode(new PackageData("/WEB-INF", "Configuration Files"))
                )
        );
    }

    private static DefaultTreeNode<PackageData> newNode(PackageData data, DefaultTreeNode<PackageData>... children) {
        if (children == null || children.length == 0) {
            return new DefaultTreeNode<>(data);
        }
        return new DefaultTreeNode<>(data, children);
    }
}

package demo.data.pojo;

public class PackageData {
	private final String path;
	private final String description;
	private final String size;

	public PackageData(String path, String description) {
		this.path = path;
		this.description = description;
		this.size = null;
	}

	public PackageData(String path, String description, String size) {
		this.path = path;
		this.description = description;
		this.size = size;
	}

	public String getPath() {
		return path;
	}

	public String getDescription() {
		return description;
	}

	public String getSize() {
		return size;
	}
}