// preload images:
		if (document.images) {
			off1_nl = new Image;
			off1_nl.src = "Image_java/1_nl.gif";
			on1_nl = new Image;
			on1_nl.src = "Image_java/1_nl_over.gif";
			off2_nl = new Image;
			off2_nl.src = "Image_java/2_nl.gif";
			on2_nl = new Image;
			on2_nl.src = "Image_java/2_nl_over.gif";
			off3_nl = new Image;
			off3_nl.src = "Image_java/3_nl.gif";
			on3_nl = new Image;
			on3_nl.src = "Image_java/3_nl_over.gif";
			off4_nl = new Image;
			off4_nl.src = "Image_java/4_nl.gif";
			on4_nl = new Image;
			on4_nl.src = "Image_java/4_nl_over.gif";
		}