var IE=document.all;
var NS=document.layers;

var previousDiv="starteBook"
function objshow(showobj) {
                if (NS) {document.layers[showobj].visibility = "show"}
                if (IE) {document.all[showobj].style.visibility = "visible"}
}
        
function objhide(hideobj) {
                if (NS) {document.layers[hideobj].visibility = "hide"}
                if (IE) {document.all[hideobj].style.visibility = "hidden"}
}
        

function changeDiv(name){
	objhide(previousDiv);
	objshow(name);
	previousDiv=name;
}


function clipValues(obj,which) {
	if (NS) {
		if (which=="t") return obj.clip.top
		if (which=="r") return obj.clip.right
		if (which=="b") return obj.clip.bottom
		if (which=="l") return obj.clip.left
	}
	else if (IE) {
		var clipv = obj.clip.split("rect(")[1].split(")")[0].split("px")
		if (which=="t") return Number(clipv[0])
		if (which=="r") return Number(clipv[1])
		if (which=="b") return Number(clipv[2])
		if (which=="l") return Number(clipv[3])
	}
}

function clipTo(obj,t,r,b,l) {
	if (NS) {
		obj.clip.top = t
		obj.clip.right = r
		obj.clip.bottom = b
		obj.clip.left = l
	}
	else if (IE) obj.clip = "rect("+t+"px "+r+"px "+b+"px "+l+"px)"
}

function clipBy(obj,t,r,b,l) {
	if (NS) {
		obj.clip.top = clipValues(obj,'t') + t
		obj.clip.right = clipValues(obj,'r') + r
		obj.clip.bottom = clipValues(obj,'b') + b
		obj.clip.left = clipValues(obj,'l') + l
	}
	else if (IE) obj.clip = "rect("+(this.clipValues(obj,'t')+t)+"px "+(this.clipValues(obj,'r')+r)+"px "+Number(this.clipValues(obj,'b')+b)+"px "+Number(this.clipValues(obj,'l')+l)+"px)"
}