function popwin(url,winname,h,w,scrollbars)
	{
	
		LeftPosition=(screen.width)?(screen.width-w)/2:100;
		TopPosition=(screen.height)?(screen.height-h)/2:100;
				
		
		window.open(url,winname,'scrollbars='+scrollbars+',menu=0,height='+h+',width='+w+',left='+LeftPosition+',top='+TopPosition);
	
	}

	
	
var prevbut = null;		

function seton(img)
	{ if (img && img.src.indexOf('_over') == -1) { img.src = img.src.replace(/\.gif/, "_over.gif"); } }

function setoff(img)
	{ if (img && img.src.indexOf('_over') > 0) { img.src = img.src.replace(/\_over.gif/, ".gif"); } }
	
	
		
	function do_nav_mouse(buttname, action)
	{

		if(action == "activate"){

			if (prevbut) {			
				setoff($(prevbut));
				// hide content.
				$('content_'+prevbut).hide();
			}
			
			prevbut = buttname;
			seton($(prevbut));
	
			// show content.
			$('content_'+buttname).show();
		}
		else if (action == "on") {
				seton($(buttname));		
		}
		else if (action == "off" && buttname != prevbut)
		{
				setoff($(buttname));		
		}
	}