title: Disable the option to scroll outside the md-dialog in AngularJS
body: <p>I have the following dialog configuration:</p>
  
  <pre><code>var position = this._mdPanel.newPanelPosition()
      .absolute()
      .center();
  
  var config = {
      attachTo: angular.element(document.body),
      controller: PanelDialogCtrl,
      controllerAs: 'ctrl',
      disableParentScroll: this.disableParentScroll,
      templateUrl: 'tmp',
      hasBackdrop: true,
      panelClass: 'form-dialog',
      position: position,
      escapeToClose:true,
      trapFocus: true,
      clickOutsideToClose: false,
      focusOnOpen: true,
      locals:{ }
  };
  
  this._mdPanel.open(config);
  </code></pre>
  
  <p>But when I scroll outside the popup it is scrolled. I want the dialog fixed to the position without any movement or something outside.</p>
  
  <p>setting <code>hasBackdrop: false</code> doesn't working.</p>