function getWindowHeight(h) {
	var windowHeight=0;
	if (typeof(window.innerHeight)=='number') {
		windowHeight=window.innerHeight;
	}
	else {
	 if (document.documentElement&&
	   document.documentElement.clientHeight) {
		 windowHeight = document.documentElement.clientHeight;
	}
	else {
	 if (document.body&&document.body.clientHeight) {
		 windowHeight=document.body.clientHeight;
	  }
	 }
	}
	return windowHeight-h; 
}