function displayTab(tab) {
// reset all tabs classes...
	document.getElementById('themes_tab').className = "";
	document.getElementById('locations_tab').className = "";
	document.getElementById('types_tab').className = "";
	document.getElementById('lifecycle_tab').className = "last";
	
// the last tab in the menu has a special class so we need to take this into consideration
	if(tab == 'lifecycle') {
		document.getElementById(tab + 'tab').className = "selected last";
	}
	else {
		document.getElementById(tab + 'tab').className = "selected";
	}

//HIDE ALL TABLES...
	document.getElementById('themes_').style.display = "none";
	document.getElementById('locations_').style.display = "none";
	document.getElementById('types_').style.display = "none";
	document.getElementById('lifecycle_').style.display = "none";
	
//...AND ONLY SHOW THE RELEVANT ONE
	document.getElementById(tab).style.display = "block";
	//alert(tab + "->" + document.getElementById(tab).style.display);
	
}