title: disable parent window when child window is open extjs 4
body: <p>In my app I have a main window with a button that opens another window. How can I disable the parent window until the child one is open?</p>
  
  <p>Code in click listener:</p>
  
  <pre><code>var editWindow = new Ext.Window({
                              id: 'editWindow',
                              width: 400,
                              layout: {
                                  type: 'vbox',
                                  align: 'stretch'
                              },
                              items: [ editPanel ],
                          });
                          editWindow.show();
  </code></pre>