function show_hide_tab(pl) {
	x = document.getElementById(pl);
	if (!(x.className.indexOf("sh") > -1 )) { // if tab is currently not showing, hide all other tabs and show 
		x.className = "sh";

		for (i=1;i<=3;i++) {
			y = "tab" + i;
			z = "click_" + y; // tab across top
			z = document.getElementById(z);
			if (y != pl) {
				document.getElementById(y).className = "hs"; // if not clicked tab, hide it
				z.className = "clicker tab_off";	
				
			} else {
				z.className = "clicker tab_on";	// click tab
			}
		}
	} 
}

function overview_agenda(pl, pid) {
	var x = "tab_overview_" + pid;
	var xm = "tab_overview_" + "menu_" + pid;
	var y = "tab_agenda_" + pid;
	var ym = "tab_agenda_" + "menu_" + pid;
	var z = "tab_abstract_" + pid;
	var zm = "tab_abstract_" + "menu_" + pid;
	switch (pl) {
		case "tab_overview_":
			document.getElementById(x).className = "sh";
			document.getElementById(xm).className = "tab_menu clicker tab_menu_selected";
			document.getElementById(y).className = "clicker hs";
			document.getElementById(ym).className = "tab_menu clicker tab_menu_gray";
			document.getElementById(z).className = "hs";
			document.getElementById(zm).className = "tab_menu clicker tab_menu_gray";
			break;
		case "tab_agenda_":
			document.getElementById(y).className = "sh";
			document.getElementById(ym).className = "tab_menu clicker tab_menu_selected";
			document.getElementById(x).className = "hs";
			document.getElementById(xm).className = "tab_menu clicker tab_menu_gray";
			document.getElementById(z).className = "hs";
			document.getElementById(zm).className = "tab_menu clicker tab_menu_gray";
			break;
		case "tab_abstract_":
			document.getElementById(z).className = "sh";
			document.getElementById(zm).className = "tab_menu clicker tab_menu_selected";
			document.getElementById(y).className = "hs";
			document.getElementById(ym).className = "tab_menu clicker tab_menu_gray";
			document.getElementById(x).className = "hs";
			document.getElementById(xm).className = "tab_menu clicker tab_menu_gray";
			break;
			
	}
}