how to add onmouseover event

I want to add an onmouseover event in this code:

[CODE]/**
* Build the html to write to the document
* IMPORTANT:
* document.write()ing the string: ‘<div style=”display:…’ will screw up nn4.x
*/
var layerTag = this.doesMenu() ? this.stringFormat(‘<div id=”{0}” style=”display: {1}” class=”{2}”>’, layerID, visibility, (nodes[i].cssClass ? nodes[i].cssClass : this.defaultClass)) : this.stringFormat(‘<div class=”{0}”>’, nodes[i].cssClass ? nodes[i].cssClass : this.defaultClass);
var onMDown = this.doesMenu() && nodes[i].n.length && nodes[i].isDynamic ? this.stringFormat(‘onmousedown=”{0}.toggleBranch(‘{1}’, true)” style=”cursor: pointer; cursor: hand”‘, this.myname, layerID) : ”;
var imgTag = this.stringFormat(‘<img src=”{0}/{1}{2}.gif” width=”20″ height=”20″ align=”top” border=”0″ name=”img_{3}” {4}>’, this.iconpath, gifname, modifier, layerID, onMDown);
var linkTarget= nodes[i].linkTarget ? nodes[i].linkTarget : this.linkTarget;
var linkStart = nodes[i].link ? this.stringFormat(‘<a href=”{0}” target=”{1}” >’, nodes[i].link, linkTarget) : ”;

var linkEnd = nodes[i].link ? ‘</a>’ : ”;

this.output += this.stringFormat(‘{0}<nobr>{1}{2}{3}{4}<span {5}>{6}</span>{7}</nobr><br></div>’,
layerTag,
prepend,
linkStart,
parentLayerID == null && (nodes.length == 1 || this.noTopLevelImages) ? ” : imgTag,
iconimg,
eventHandlers,
nodes[i].title,
linkEnd);[/CODE]

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