function dropCategory(obj)
{   var x=document.getElementById('objdropXT').value
	if(obj.id.substr(0,2) == "xt")
	{
		if(obj.className == "on")
		{
			obj.className = "off";
			x= "";	
		}
		else
		{
			obj.className = "on";
			if(x != "")
			{
				identity=document.getElementById(x);
				identity.className = "off";
				
			}
			x = obj.id;
			
		}
	}
}