ns4 = (document.layers)? true:false;
ie4 = (document.all)? true:false;

var disp = "non";

function apparaitre() {
	if (ns4) {
		document.context.visibility = 'visible';
		disp = "oui";
		}
	if (ie4) {
		context.style.visibility = 'visible';
		disp = "oui";
		}
	}

function disparaitre() {
	if (ns4) {
		if ( disp == "ouioui" ) {
			document.context.visibility = 'hidden';
			}
		if ( disp == "oui" ) {
			disp = "ouioui";
			}
		}
	if (ie4) {
		if ( disp == "ouioui" ) {
			context.style.visibility = 'hidden';
			}
		if ( disp == "oui" ) {
			disp = "ouioui";
			}
		}
	}