function getElementPosition(elemID) {
	var offsetTrail = document.getElementById(elemID);
	var offsetLeft = 0;
	var offsetTop = 0;
	
	while (offsetTrail){
		offsetLeft += offsetTrail.offsetLeft;
		offsetTop += offsetTrail.offsetTop;
		offsetTrail = offsetTrail.offsetParent;
	}
	
	if (navigator.userAgent.indexOf('Mac') != -1 && typeof document.body.leftMargin != 'undefined') {
		offsetLeft += document.body.leftMargin;
		offsetTop += document.body.topMargin;
	}
	
	return {left:offsetLeft,top:offsetTop};
}		

function getElement( whichLayer ) {
	var elem;
	
	if( document.getElementById ) { // this is the way the standards work
		elem = document.getElementById( whichLayer );
	} else if( document.all ) {// this is the way old msie versions work
		elem = document.all[whichLayer];
	} else if( document.layers ) {// this is the way nn4 works
		elem = document.layers[whichLayer];
	}
	
	return elem;
}

function toggleLayer( whichLayer ) {
	var elem = getElement( whichLayer );
	var vis = elem.style;
	
	// if the style.display value is blank we try to figure it out here
	if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined) {
		vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
	}
	
	vis.display = (vis.display==''||vis.display=='block')?'none':'block';
}

function layerHide( whichLayer ) {
	var elem = getElement( whichLayer );
	var vis = elem.style;
	
	// if the style.display value is blank we try to figure it out here
	if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined) {
		vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
	}
	
	vis.display = 'none';
}

function layerShow( whichLayer, parent, offset ) {
	var elem = getElement( whichLayer );
	var vis = elem.style;
	
	// if the style.display value is blank we try to figure it out here
	if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined) {
		vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
	}

	var coord = getElementPosition(parent);
	vis.top = (coord.top + offset) + "px";
	vis.left = coord.left + "px";
	
	vis.display = 'block';
	vis.backgroundPosition = 'top';
}

function hideboth() {
	layerHide('addmenuhere');
	layerHide('designmenu');
	layerHide('engineermenu');
}

function showdesignmenu() {
	layerHide('addmenuhere');
	layerHide('engineermenu');
	layerShow('designmenu', 'designGuides', 17);
}

function showengineermenupanel() {
	layerHide('addmenuhere');
	layerHide('designmenu');
	layerShow('engineermenu', 'engineerInfo', 17);
}

function hidedesignmenu() {
	layerHide('designmenu');
	layerHide('engineermenu');
}

function showmenu() {
	layerHide('designmenu');
	layerHide('engineermenu');
	layerShow('addmenuhere', 'environmentalInfo', 17);
}

function hidemenu() {
	layerHide('addmenuhere');
	layerHide('engineermenu');
}