function showTab(showtab, maxtab){	
	for(var i=1; i<=maxtab; i++){
		if(document.getElementById('tab_'+i)){
			if(i==showtab){
				document.getElementById('tab_'+i).style.display = 'block';
				setTabState(i, "selected");
			}
			else{
				document.getElementById('tab_'+i).style.display = 'none';
				setTabState(i, "normal");
			}
		}		
	}
}
function mouseOverTab(showtab){			
	if(document.getElementById('tabbtn_'+showtab).className.indexOf('selected') == -1){
		setTabState(showtab, "hover");
	}
}
function mouseOutTab(showtab){	
	if(document.getElementById('tabbtn_'+showtab).className.indexOf('selected') == -1){
		setTabState(showtab, "normal");
	}
}
function setTabState(showtab, newState) {
	var className = document.getElementById('tabbtn_'+showtab).className;
	className = className.split(" ")[0];  // take first word of classname
	className += " " + newState
	document.getElementById('tabbtn_'+showtab).className = className;
}