DHTMLX window cannot be resized if open over a loaded tabbar

If a window is opened over a loaded tabbar content, the window cannot be resized bigger. It can only be resized smaller. Please see the sample code below:

<!DOCTYPE html>
  <title>Popup window over tabbar content</title>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
  <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
  <link rel="stylesheet" type="text/css" href="dhtmlx.css"/>
  <script src="dhtmlx.js"></script>
    html, body {
      width: 100%;
      height: 100%;
      margin: 0px;
      padding: 0px;
      overflow: hidden;
<body onload="doOnLoad();">
    var myLayout, myTabbar,dhxWins;
    function doOnLoad() {
      myLayout = new dhtmlXLayoutObject(document.body, "1C");
      toolbar = myLayout.cells("a").attachToolbar();
      toolbar.addButtonTwoState("create", 0, "Create window");
      toolbar.attachEvent("onStateChange", function(id, state){
      myTabbar = myLayout.cells("a").attachTabbar({
        tabs: [
          { id: "a1", text: "Tab 1", active: true },
          { id: "a2", text: "Tab 2" }
      dhxWins = new dhtmlXWindows();
    function createWindow() {
      var tranWin = dhxWins.createWindow("popup", 100, 200,500, 200);

Thank you for your post.
The problem is confirmed. We’ll inform You if it can be fixed in the near future.