How to NotiFy Single Item or Record or Single Column from ZK List Not Whole List?

ZUL file

<?page title="new page title" contentType="text/html;charset=UTF-8"?>
<zk> <br /> <window title="new page title" border="normal" id="inp" <br /> viewModel="@id('vm') @init('com.notify.MyListbox')" apply="org.zkoss.bind.BindComposer" > <br /> <button label="AddItem" onClick="@command('addNewItem')<a href="mailto:%22%20%3e%3c/button%3e%20%3cbr%20/%3e%20%3cbr%20/%3e%20%3cbr%20/%3e%20%3clistbox%20model=%22@bind(vm.dataList)">" ></button> <br /> <br /> <br /> <listbox model="@bind(vm.dataList)</a><a href="mailto:%22%20selectedItem=%22@bind(vm.selectedItem)">" selectedItem="@bind(vm.selectedItem)</a>" > <br /> <listhead> <br /> <listheader value="A"></listheader> <br /> <listheader value="B"></listheader> <br /> <listheader value="C"></listheader> <br /> <br /> </listhead> <br /> <template name="model" var="mymodel"> <br /> <listitem> <br /> <listcell> <br /> <br /> <textbox value="@bind(mymodel.a)" onChange="@command('changeTextBox',data = mymodel)<a href="mailto:%22/%3e%20%3cbr%20/%3e%20%3c/listcell%3e%20%3cbr%20/%3e%20%3clistcell%3e%20%3cbr%20/%3e%20%3ctextbox%20value=%22@bind(mymodel.b)">"/> <br /> </listcell> <br /> <listcell> <br /> <textbox value="@bind(mymodel.b)</a>" onChange="@command('changeAnotherTextBox',data = mymodel)<a href="mailto:%22/%3e%20%3cbr%20/%3e%20%3cbr%20/%3e%20%3c/listcell%3e%20%3cbr%20/%3e%20%3clistcell%3e%20%3cbr%20/%3e%20%3clabel%20value=%22@bind(mymodel.c)">"/> <br /> <br /> </listcell> <br /> <listcell> <br /> <label value="@bind(mymodel.c)</a>" /> <br /> <br /> </listcell> <br /> </listitem> <br /> </template> <br /> </listbox> <br /> </window> <br /></zk>  
JAVA:

package com.notify;

import java.util.ArrayList;
import java.util.List;

import org.zkoss.bind.BindUtils;
import org.zkoss.bind.annotation.AfterCompose;
import org.zkoss.bind.annotation.BindingParam;
import org.zkoss.bind.annotation.Command;
import org.zkoss.bind.annotation.ContextParam;
import org.zkoss.bind.annotation.ContextType;
import org.zkoss.bind.annotation.NotifyChange;
import org.zkoss.zk.ui.Component;

// TODO: Auto-generated Javadoc
/**
* The Class MyListbox.
*/
public class MyListbox {

/** The data list. */
private List<Data> dataList;

/** The selected item. */
private Data selectedItem;

/**
* After compose.
*
* @param view the view
*/
@AfterCompose
public void afterCompose(@ContextParam(ContextType.VIEW) Component view) {
try {
dataList = new ArrayList<Data>();
Data data;
data = new Data("a1", "b1", "c1");
dataList.add(data);
data = new Data("a2", "b2", "c2");
dataList.add(data);
data = new Data("a3", "b3", "c3");
dataList.add(data);
} catch (Exception e) {

}
}

/**
* Change text box.
*
* @param data the data
*
* Taken from ZK Forum
*/
@Command
public void changeTextBox(@BindingParam("data") Data data) {
data.setB("Hariom=>" + data.getA());
BindUtils.postNotifyChange(null, null, data, "b");
}

/**
* Change another text box.
* Praposed By Nitin
*/
@Command
public void changeAnotherTextBox() {
selectedItem.setC("Hariom=>" + selectedItem.getB());
BindUtils.postNotifyChange(null, null, selectedItem, "c");
}



/**
* Adds the new item.
*/
@Command
@NotifyChange("dataList")
public void addNewItem() {
Data data = new Data("", "", "");
dataList.add(data);
}

/**
* Gets the data list.
*
* @return the data list
*/
public List<Data> getDataList() {
return dataList;
}

/**
* Sets the data list.
*
* @param dataList the new data list
*/
public void setDataList(List<Data> dataList) {
this.dataList = dataList;
}

/**
* The Class Data.
*/
public class Data {

/** The a. */
String a;

/** The b. */
String b;

/** The c. */
String c;

/**
* Gets the a.
*
* @return the a
*/
public String getA() {
return a;
}

/**
* Gets the b.
*
* @return the b
*/
public String getB() {
return b;
}

/**
* Gets the c.
*
* @return the c
*/
public String getC() {
return c;
}

/**
* Sets the a.
*
* @param a the new a
*/
public void setA(String a) {
this.a = a;
}

/**
* Sets the b.
*
* @param b the new b
*/
public void setB(String b) {
this.b = b;
}

/**
* Sets the c.
*
* @param c the new c
*/
public void setC(String c) {
this.c = c;
}

/**
* Instantiates a new data.
*
* @param a the a
* @param b the b
* @param c the c
*/
public Data(String a, String b, String c) {
super();
this.a = a;
this.b = b;
this.c = c;
}

}

/**
* Gets the selected item.
*
* @return the selected item
*/
public Data getSelectedItem() {
return selectedItem;
}

/**
* Sets the selected item.
*
* @param selectedItem the new selected item
*/
public void setSelectedItem(Data selectedItem) {
this.selectedItem = selectedItem;
}

}