drag.zul.xml

<window apply="org.zkoss.bind.BindComposer" viewModel="@id('vm') @init('org.zkoss.mvvm.examples.duallistbox.DragVM')">
	
	<hlayout>
		<vlayout>
			List1
			<listbox model="@bind(vm.list1)" width="300px" height="300px" droppable="true"
			onDrop="@command('dropToList1',item=event.dragged.attributes.item)">
				<template name="model">
					<listitem draggable="true" droppable="true"
					label="@load(each.name)" attributes.item="@load(each)"
					onDrop="@command('insertToList1',item=event.dragged.attributes.item, base=each)"/>
				</template>
			</listbox>
		</vlayout>
		<vbox vflex="1" pack="middle" width="100px">
			
		</vbox>
		<vlayout>
			List2
			<listbox model="@bind(vm.list2)" width="300px" height="300px" droppable="true"
			onDrop="@command('dropToList2',item=event.dragged.attributes.item)">
				<template name="model">
					<listitem draggable="true" droppable="true" 
					label="@load(each.name)" attributes.item="@load(each)"
					onDrop="@command('insertToList2',item=event.dragged.attributes.item, base=each)"/>
				</template>
			</listbox>
		</vlayout>
	</hlayout>
</window>

DragVM.java

package org.zkoss.mvvm.examples.duallistbox;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.zkoss.bind.annotation.BindingParam;
import org.zkoss.bind.annotation.Command;
import org.zkoss.bind.annotation.NotifyChange;

public class DragVM {

	 List<Item> list1;

    List<Item> list2;
    /**
     * Initialize the view model with fetching the ATS configurations data for the first time.
     */
    @Init
    public void init()
    {
        list1 = new ArrayList<Item>();

        list2 = new ArrayList<Item>();

        for (int i=0;i<10;i++){

            list1.add(new Item("Item "+i));

        }
    }

    public List<Item> getList1() {

        return list1;

    }

    public List<Item> getList2() {

        return list2;

    }

    @Command
    @NotifyChange({"list1","list2"})
    public void dropToList1(@BindingParam("item") Item item){

        if (item != null)
        {
            if (this.list1.contains(item))
            {
                this.list1.remove(item);
            }
            this.list1.add(item);
            this.list2.remove(item);
        }

    }

    @Command
    @NotifyChange({"list1","list2"})
    public void dropToList2(@BindingParam("item") Item item){


        if (item != null)
        {
            if (this.list2.contains(item))
            {
                this.list2.remove(item);
            }
            this.list2.add(item);
            this.list1.remove(item);
        }

    }

    @Command
    @NotifyChange({"list1","list2"})
    public void insertToList1(@BindingParam("base") Item base,@BindingParam("item") Item item){

        if (item != null && base != null && this.list1.contains(base) && this.list2.contains(item))
        {
            this.list1.add(this.list1.indexOf(base), item);
            this.list2.remove(item);
        }
        if (item != null && base != null && this.list1.contains(base) && !this.list2.contains(item))
        {
            Collections.swap(this.list1, this.list1.indexOf(base), this.list1.indexOf(item));
        }

    }

    @Command
    @NotifyChange({"list1","list2"})
    public void insertToList2(@BindingParam("base") Item base,@BindingParam("item") Item item){

        if (item != null && base != null && this.list2.contains(base) && this.list1.contains(item))
        {
            this.list2.add(this.list2.indexOf(base), item);
            this.list1.remove(item);
        }
        if (item != null && base != null && this.list2.contains(base) && !this.list1.contains(item))
        {
            Collections.swap(this.list2, this.list2.indexOf(base), this.list2.indexOf(item));
        }

    }

    static public class Item{

        String name;

        public Item(String name){

            this.name = name;

        }

        public String getName() {

            return name;

        }

        public void setName(String name) {

            this.name = name;

        }

    }
}