window.onresize = doResize;
doResize();   

function doResize() {

    winW = window.innerWidth;
    winH = window.innerHeight;
    if (navigator.appName.indexOf("Microsoft") != -1) {
        winW = document.body.offsetWidth;
        winH = document.body.offsetHeight;
    }
    
    var mainDiv = dojo.byId("mainDiv");
    var width = 0;
    width = winW*0.8;
       
    if (width < 900) {
        width = 900;
    }
    width=900;
    
    mainDiv.style.width = width + "px";
    mainDiv.style.height = "auto";
    
    mainDiv.style.left = (winW - width)/2 + "px";
    if ((winW - width) < 0) mainDiv.style.left = "0px"; 
    mainDiv.style.top = "0px"; 
    mainDiv.style.fontSize = (width/60)+"px";
    mainDiv.style.display = "block";
}
/*
window.onbeforeunload = function (evt) {
	if (onunloadquestion) {
		var message = ".אזהרה! הינך עומד\\ת לעזוב את העמוד"
		if (typeof(evt) == "undefined") {
			evt = window.event;
		}
		if (evt) {
			evt.returnValue = message;
		}
		return message;
	}
}
*/