Labels in the list box should get bold or default at runtime on click

Listcell lc = new Listcell();
lstm.appendChild(lc);//lstm is your Listitem
final Label lbl = new Label("My content");
lc.appendChild(lbl);
lstm.addEventListener("onClick", new EventListener() {

            public void onEvent(Event e) throws Exception {
                lbl.setStyle("font-weight:bold;");//or  lbl.setSclass("bold"); if you have a specified class called "bold"
            }
        });

<window title="Listbox" border="normal">
	<listbox>	
		<listitem>
<attribute name="onClick"><![CDATA[
 lbl.setStyle("font-weight:bold;");//or  lbl.setSclass("bold"); if you have a specified class called "bold"
 ]]></attribute>
			<listcell ><label id="lbl" value="This is my content"/></listcell>
		</listitem>
	</listbox>
</window>

<style>
	tr.seld,td.seld,tr.z-listitem-seld div.z-listcell-cnt{
		font-weight: bold;
	}
</style>

<?init class="org.zkoss.zkplus.databind.AnnotateDataBinderInit"?>
<zk>
	<zscript>
		class invItem {
			private String itemu;
			private String item;
			private String itemName;			

			public invItem (String iu, String i, String n ) {
				itemu = iu;
				item = i;
				itemName = n;
			}
			
			public String getItemu() {
				return itemu;
			}
			public void setItemu(String itemu) {
				this.itemu = itemu;
			}
			public String getItem() {
				return item;
			}
			public void setItem(String item) {
				this.item = item;
			}
			public String getItemName() {
				return itemName;
			}
			public void setItemName(String itemName) {
				this.itemName = itemName;
			}			
		}
		 
		List invItems = new ArrayList();

		invItems.add(new invItem("SKU18237", "44537", "Lorem ipsum dolor sit amet"));
		invItems.add(new invItem("SKU21410", "32414", "Ut molestie mattis elit ac posuere"));
		invItems.add(new invItem("SKU44234", "40855", "Sed imperdiet aliquam augue"));
		invItems.add(new invItem("SKU32869", "85002", "Vivamus molestie nunc in elit posuere egestas"));
		invItems.add(new invItem("SKU85002", "66804", "Aliquam commodo, sem at dapibus hendrerit"));
		invItems.add(new invItem("SKU58119", "58119", "In sit amet turpis eget urna dapibus vehicula"));
		invItems.add(new invItem("SKU79127", "87138", "Nulla egestas justo non tellus eleifend vel accumsan"));
		invItems.add(new invItem("SKU21410", "21410", "Quisque id orci ante"));
		invItems.add(new invItem("SKU58119", "41315", "Donec ac arcu sed mauris rhoncus dictum vel vel arcu"));
		invItems.add(new invItem("SKU21410", "35128", "Donec ut lacus ut leo dapibus ornare id ac quam"));
		invItems.add(new invItem("SKU11193", "11193", "Nulla a leo vitae nisl mattis ullamcorper suscipit a metus"));
		invItems.add(new invItem("SKU34544", "34544", "Vestibulum a eros in diam tincidunt aliquet"));
		invItems.add(new invItem("SKU85011", "89174", "Nullam bibendum libero imperdiet ipsum sollicitudin sollicitudin"));

	</zscript>
	
	<style>
		tr.seld,td.seld,tr.z-listitem-seld div.z-listcell-cnt{
			font-weight: bold;
			font-size: 1.5em;
		}
	</style>
	
	<window>
		<listbox model="@{invItems}" >
			<listhead >
				<listheader label="SKU" />
				<listheader label="Item" />
				<listheader label="Name" />
			</listhead>
			<listitem id="li1" self="@{each=invItem}">
				<listcell label="@{invItem.itemu}"/>	
				<listcell label="@{invItem.item}"/>
				<listcell label="@{invItem.itemName}"/>
			</listitem>	
		</listbox>
	</window>
</zk>

<zk>
	<style>
		tr.seld,td.seld,tr.z-listitem-seld div.z-listcell-cnt{
			font-weight: bold;
			font-size: 1.5em;
		}
	</style>

</zk>