var Scroller = {
			element: null,
			callback_up: null,
			callback_down: null,
			speed: 10,
			
			set_element: function(element)
			{
				if(typeof element == 'string')
				{
					element = document.getElementById(element);
					if(!element)
					{
						throw Error('Element not found');
					}
				}
				
				this.element = element;
			},
			
			up: function()
			{
				this.element.scrollTop -= this.speed;
				
				this.callback_up = window.setTimeout("Scroller.up();", 50);
			},
			
			cancel_up: function()
			{
				window.clearTimeout(this.callback_up);
			},
			
			down: function()
			{
				this.element.scrollTop += this.speed;			
				
				this.callback_down = window.setTimeout("Scroller.down();", 50);
			},
			
			cancel_down: function()
			{
				window.clearTimeout(this.callback_down);	
			}
		};