function show_tab(tab_number) {
		var open_tab = document.getElementById("tc_"+tab_number);
		var open_tab_label = document.getElementById("tab_"+tab_number);
		for (i = 1; i < 4; i++) {
			var tab = document.getElementById("tc_"+i);
			var tab_label = document.getElementById("tab_"+i);
			if (tab != null && tab != open_tab) {
				tab.style.display="none";
			}
			tab_label.className="not_current_tab";
		}
		if (open_tab != null) {
			open_tab.style.display="block";
		}
		open_tab_label.className="current";
		document.getElementById("footer").style.display = "none";
		document.getElementById("footer").style.display = "block";
		}