function toggle(el, trigger) {
	if(el.style.display != 'none') { 
		el.style.display = 'none'; 
		if(trigger != undefined) {
			trigger.innerHTML = trigger.innerHTML.replace('hide', 'show');
		}
	} else { 
		el.style.display = ''; 
		if(trigger != undefined) {
			trigger.innerHTML = trigger.innerHTML.replace('show', 'hide');
		}

	}
}

function showTab(tab) {
	tab_name = "gt_tab_"+tab
	divs = document.getElementsByTagName('div'); 
	for(i = 0; i < divs.length; ++i) {
		if(divs[i].className == 'gt_tab') {
			if(divs[i].id == tab_name) {
				divs[i].style.display = '';
			} else {
				divs[i].style.display = 'none';
			}
		}
	}
	tab_top_name = tab_name+"_top";
	as = document.getElementsByTagName('a'); 
	for(i = 0; i < as.length; ++i) {
		if(as[i].className == 'gt_tab_top') {
			if(as[i].id == tab_top_name) {
				as[i].style.backgroundColor = 'lightgray';
			} else {
				as[i].style.backgroundColor = 'white';
			}
		}
	}
}