function myMove(target, size, item) {
		// top wert
		var acttop = document.getElementById(target).style.top;
		var acttop = Number(acttop.substring(0, acttop.length-2));
		// gesamthöhe des divs
		var actheight = document.getElementById(target).offsetHeight;
		
		var item_fw = item + "_fw";
		var item_back = item + "_back";
		
		if (size > 0) //wenn verschieben nach unten
		{
			if( (acttop + size) == 0)
			{
				$(item + '_back').setStyle({ display: 'none' });
			}
			
			if (acttop < 0) 
			{
				new Effect.Move($(target), { x: 0, y: size, mode: 'relative' });
				$(item + '_fw').setStyle({ display: 'block' });
			}
			
			
		} else { //wenn verschieben nach unten
			
			if (actheight + acttop + size <= -size )
			{
				$(item + '_fw').setStyle({ display: 'none' });
			}
			
			if (actheight + acttop > -size ) 
			{
				
				new Effect.Move($(target), { x: 0, y: size, mode: 'relative' });
				// zurueck sichtbar stellen
				$(item + '_back').setStyle({ display: 'block' });
			}
		}
	}