function tree( strElementId ){
	if( document.all ) {
	
		if( "visible" == document.all(strElementId).style.visibility ) {
			document.all(strElementId).style.visibility = "hidden";
			document.all(strElementId).style.display = "none";
		}else{
			document.all(strElementId).style.visibility = "visible";
			document.all(strElementId).style.display = "block";
		}
	} else if ( document.getElementById ){
		if( "visible" == document.getElementById(strElementId).style.visibility ) {
			document.getElementById(strElementId).style.visibility = "hidden";
			document.getElementById(strElementId).style.display = "none";
		}else{
			document.getElementById(strElementId).style.visibility = "visible";
			document.getElementById(strElementId).style.display = "block";
		}
	}
}