function makeVisibleOn(elt){
	document.getElementById(elt).style['display'] = 'block';
}

function makeVisibleOff(elt){
	document.getElementById(elt).style['display'] = 'none';
}


function makeScrollbar(content,scrollbar,handle,horizontal,ignoreMouse){
		var steps = (horizontal?(content.getSize().scrollSize.x - content.getSize().size.x):(content.getSize().scrollSize.y - content.getSize().size.y))
		var slider = new Slider(scrollbar, handle, {	
			steps: steps,
			mode: (horizontal?'horizontal':'vertical'),
			onChange: function(step){
						// Scrolls the content element in x or y direction.
						var x = (horizontal?step:0);
						var y = (horizontal?0:step);
						content.scrollTo(x,y);
			}
		}).set(0);
		if( !(ignoreMouse) ){
						// Scroll the content element when the mousewheel is used within the 
						// content or the scrollbar element.
						$$(content, scrollbar).addEvent('mousewheel', function(e){	
							e = new Event(e).stop();
							var step = slider.step - e.wheel * 30;	
							slider.set(step);					
						});
		}
		// Stops the handle dragging process when the mouse leaves the document body.
		$(document.body).addEvent('mouseleave',function(){slider.drag.stop()});
}

function openPopup(url, width, height) {
	var x		= Math.round((screen.width - width) / 2);
	var y		= Math.round((screen.height - height) / 2);
	var param	= 'width='+width+',height='+height+',dependent=yes,left='+x+',top='+y+',resizable=0,toolbar=0,scrollbars=0,status=0,menubar=0';
	var newWin	= window.open(url, "popup", param);
	return false;
}