// image preloader
	function preload( image_names )
	{
		var name;
		var i;
		if( document.images ){
			for( i = 0; i < image_names.length; ++i ){
				var temp = new Image();
				temp.src = image_names[ i ];
			}
		}
	}

// image swapper
	var swapped_images = new Array;
	function change( image_name, image_src )
	{
		swapped_images[ image_name ] = document.images[ image_name ].src;
		document.images[ image_name ].src = image_src;
	}
	function restore( image_name )
	{
		document.images[ image_name ].src = swapped_images[ image_name ];
	}