function MainMenu(){
 
	var OldImage;
	var OldText;
	this.getOldImage = function(obj){document.getElementById(obj).style.background = OldImage; };
	this.setOldImage = function(obj){ OldImage = document.getElementById(obj).style.background;};
	this.chgText = function (obj , newText) { OldText = document.getElementById(obj).innerHTML; document.getElementById(obj).innerHTML=newText;};
	this.chgImage = function(obj , newImage){
		if(newImage != null){
			this.setOldImage(obj);
			this.chgText('che' , '');
			document.getElementById(obj).style.background = 'url('+newImage+') no-repeat';
		} else {
			document.getElementById(obj).innerHTML = OldText;
			document.getElementById(obj).style.background = OldImage; 
		}
	}

}

var Menu = new MainMenu();