var Scroller = {
	
	speed: 90
	
	, walkSize: 10
	
	, CONST_UP : 1
	
	, CONST_DOWN : 2
	
	, animation : null
	
	, up: function( idElement )
	{
		if( this.animation ) return;
		this.animation = setInterval( 'Scroller.walkUp( "' + idElement + '" )' , this.speed );
	} 
	
	, down: function( idElement )
	{
		if( this.animation ) return;
		this.animation = setInterval( 'Scroller.walkDown( "' + idElement + '" )' , this.speed );
	}
	
	, stop: function( idElement )
	{
		clearInterval( this.animation );
		this.animation = null;
	}
	
	, walkDown: function( idElement )
	{
		var objElement = document.getElementById( idElement );
		
		if( ( objElement.scrollTop + this.walkSize ) >= objElement.scrollHeight )
		{
			objElement.scrollTop = objElement.scrollHeight;
			clearInterval( this.animation );
		}
		else
		{
			objElement.scrollTop += this.walkSize;
		}
	}
	
	, walkUp: function( idElement )
	{
		var objElement = document.getElementById( idElement );
		
		if( ( objElement.scrollTop - this.walkSize ) <= 0 )
		{
			objElement.scrollTop = 0;
			clearInterval( this.animation );
		}
		else
		{
			objElement.scrollTop -= this.walkSize;
		}
	}
	
}