function swap_image(image_id)
{
	image = document.getElementById(image_id+'-link');
	if(image)
	{
		image_name = image.src
		if(image_name.indexOf('over') >= 0)
		{
			image.src = image_name.replace('-over', '');
		}
		else
		{
			image.src = image_name.replace('.png', '-over.png');
		}
	}
}