window.onerror = null;

//initialise all variables

var olddiv = 0;   //this will become a reference to the object that is being shown or was last shown
                  //in all cases, the object that is shown/hidden will be a <div ..> element

function getRefToDivNest( divID, oDoc ) {
	if( !oDoc ) { oDoc = document; }
	if( document.layers ) {
		if( oDoc.layers[divID] ) { return oDoc.layers[divID]; } else {
			for( var x = 0, y; !y && x < oDoc.layers.length; x++ ) {
				y = getRefToDivNest(divID,oDoc.layers[x].document); }
			return y; } }
	if( document.getElementById ) { return document.getElementById(divID); }
	if( document.all ) { return document.all[divID]; }
	return document[divID];
}

function showdiv(thisdiv) {
	//this function shows the div
	hidediv(); //first, hide the last one
	//Convert the name of the div into a reference to it. Basically, get a reference to the object
	olddiv = getRefToDivNest(thisdiv);
	if( !olddiv ) {
		//Nothing found. This browser is not compliant with any!
		notifyFail();
		return;
	}
	//Make the object visible
	if( olddiv.style ) {
		//DOM compliant
		olddiv.style.visibility = 'visible';
	} else {
		if( olddiv.visibility ) {
			//Netscape and old versions of Mozilla compliant
			olddiv.visibility = 'show';
		} else {
			//Nothing found, no known way of changing the style
			notifyFail();
			return;
		}
	}
	divshown = 1;
}

function hidediv() {
	if( olddiv ) {
		if( olddiv.style ) {
			//DOM compliant
			olddiv.style.visibility = 'hidden';
		} else {
			//Netscape and old versions of Mozilla compliant
			olddiv.visibility = 'hide';
		}
		//No need for else notifyFail()
		//If it was going to fail, it would have failed while it was being shown
	}
	olddiv = false;
}

function notifyFail() {
	//oops, I guess nothing works in this browser
	if( window.myalternative ) {
		if( window.confirm( "You are having problems displaying some components of this page.\n"+
			"\nWould you like to try the other page design?" ) ) { location.href = myalternative; }
	} else {
		window.alert( "You are having problems displaying some components of this page.\n\n"+
			"Sorry, but there is not yet an alternative page." );
	}
}