var displaywindow = null

function newWindow(url, window_width, window_height, is_scrollbars){

   var window_left = (screen.availWidth - window_width) / 2;
   var window_top = (screen.availHeight - window_height) / 4;

	if (displaywindow && displaywindow.open) {
			displaywindow.close();
	}

   displaywindow = window.open(url, 'QuickWindow', 'width=' + window_width + ', height=' + window_height + ', left=' + window_left + ', top=' + window_top + ', location=0, menubar=0, resizable=0, scrollbars=' + is_scrollbars + ', alwaysRaised')
}