var slideIntervalId = null;
var pixel_diff = -127;


function startSlide(id)
{
	pixel_diff = -127 - pixel_diff;
	clearInterval(slideIntervalId);
	slideIntervalId = setInterval("slide('" + id + "', " + pixel_diff + ");", 1);
}

function slide(id, bottom)
{
	var element = document.getElementById(id);

	var nextSize;

	if(parseInt(element.style.bottom) == bottom)
	{
		  clearInterval(slideIntervalId);
		  return;
	}
	else if(parseInt(element.style.bottom) > bottom)
	{
		  nextSize = parseInt(element.style.bottom) - 1;
	}
	else
	{
		  nextSize = parseInt(element.style.bottom) + 1;
	}

	element.style.bottom = nextSize + "px";
}