title: ExtJS: dynamically ajust layout after adding/removing some form fields
body: <p>I have form layout with some TextField elements and one HtmlEditor element. Some TextField elements are "hideable", i.e. could be hid or showed. After hiding/showing elements HtmlEditor instance break layout — there appear empty space or element doesn't end at the window border.</p>
  
  <p>Is it possible to tell to HtmlEditor instance use all remaining available space? Even in case when some elements are hidden/showed.</p>
  
  <p>I've tried to use <code>anchor</code> property, but it works well until some element removed from the layout.</p>
  
  <p><strong>Updated</strong>
  Here is a sample code:</p>
  
  <pre><code>var htmlEditor = new Ext.form.HtmlEditor({
      anchor: '100% -54',
      hideLabel: true
  });
  
  var fp = new Ext.form.FormPanel({
      items: [{xtype: 'textfield', fieldLabel: 'zzz', mode: 'local'}, 
              {xtype: 'textfield', fieldLabel: 'nnn', id: 'id-one', mode: 'local'},
          htmlEditor]
  });
  
  var w = new Ext.Window({layout: 'fit',
      height: 400, width: 600,
      tbar: [{text: 'click',
          handler: function() {
              // hide element
              Ext.getCmp('id-one').getEl().up('.x-form-item').setDisplayed(false);
              w.doLayout();
          }
          }],
      items: fp   
  });
  
  w.show();
  </code></pre>
  
  <p>Execute, click toolbar button "click", one field should disappear, then look at empty space below htmleditor.</p>