function hideLevel( _levelId) {
	var thisLevel = document.getElementById( _levelId );
	thisLevel.style.display = "none";
	}
	
function showLevel( _levelId) {
	var thisLevel = document.getElementById( _levelId );
	if ( thisLevel.style.display == "none") {
		thisLevel.style.display = "block";
		}
	else {
		hideLevel( _levelId);
		}	
	}

function showLevelOver( _levelId) {
	var thisLevel = document.getElementById( _levelId );
	if ( thisLevel.style.display == "none") {
		thisLevel.style.display = "block";
		}
	}