I want a FormPanel but with the Save button inside the main panel area and not in the button footer. Instead of writing my own custom clientvalidation just for that special case, I made an override that handles a formBind anywhere in the "items" part of the FormPanel.

The reason why you may want this is if you have a single row FormPanel using a column layout, for example your layout could be like so:

Code:
Field Label1:  Field Label2:  Field Label3:    Save
TextField      TextField      TextField        Button
This is Ext 3.0.0 code
Code:
Ext.override(Ext.FormPanel, {
  initComponent : function(){
    this.form = this.createForm();
    Ext.FormPanel.superclass.initComponent.call(this);

    this.bodyCfg = {
      tag: 'form',
      cls: this.baseCls + '-body',
      method : this.method || 'POST',
      id : this.formId || Ext.id()
    };
    if(this.fileUpload) {
      this.bodyCfg.enctype = 'multipart/form-data';
    }
    this.initItems();

    this.addEvents(
      /**
       * @event clientvalidation
       * If the monitorValid config option is true, this event fires repetitively to notify of valid state
       * @param {Ext.form.FormPanel} this
       * @param {Boolean} valid true if the form has passed client-side validation
       */
      'clientvalidation'
    );

    this.additionalFormBinds = this.find("formBind", true);

    this.relayEvents(this.form, ['beforeaction', 'actionfailed', 'actioncomplete']);
  },

  bindHandler : function(){
    var valid = true;
    this.form.items.each(function(f){
      if(!f.isValid(true)){
        valid = false;
        return false;
      }
    });

    if ( this.fbar || this.additionalFormBinds.length ) {
      var form_binds = [];

      this.fbar                       && form_binds.push(this.fbar.items.items);
      this.additionalFormBinds.length && form_binds.push(this.additionalFormBinds);

      for ( var i = 0, len1 = form_binds.length; i < len1; i++ ) {
        var fitems = form_binds[i];

        for ( var j = 0, len2 = fitems.length; j < len2; j++ ) {
          var btn = fitems[j];
          if( btn.formBind === true && btn.disabled === valid ) {
            btn.setDisabled(! valid);
          }
        }
      }
    }

    this.fireEvent('clientvalidation', this, valid);
  }
});