title: How to check if window is already open before opening a new one
body: <p>I am creating a window on click of a button. If I click the button more than once, it opens a window each time I click on it. How can I check first if the window is already open? If open close it and if not open a new one.</p>
  
  <p>I am using following code to show window using extjs.</p>
  
  <pre><code>var modiwin = Ext.create('widget.window', {
      height: 70,
      width: 110,
      title: 'Editing',
      closable: true,
      autoScroll: false,
      collapsible: true,
      //modal:'True',
      maximizable: false,
      resizable:false,
      items: [mdsavebtn,mddelbtn]
  });
  modiwin.setPosition(175,55);
  modiwin.show();
  </code></pre>