var img_enable = new Image();
img_enable.src = "images/enable_tooltip.jpg";
var img_disable = new Image();
img_disable.src = "images/disable_tooltip.jpg";
btc.style.visibility="visible";

function enableDisable()
	{
		btc=document.getElementById("btc");
		tooltip_button=document.getElementById("tooltip_button");
	
		if(btc.style.visibility=="visible")
			{
				btc.style.visibility="hidden";
				tooltip_button.src = img_enable.src;
				//alert("1");
			}
		else
			{
			btc.style.visibility="visible";
			tooltip_button.src = img_disable.src;
				//alert("2");
			}		
	}