title: How to determine used ckeditor configuration
body: <p>i have a custom ckeditor plugin with a custom dialog.
  The dialog is added like this:</p>
  
  <pre><code>    var dialog_file = this.path + 'dialogs/customdialog.js' ;
      CKEDITOR.dialog.add( pluginName, dialog_file);
  </code></pre>
  
  <p>I would like to determine in the dialog which ckeditor config is loaded. I can make assumptions based on that and set the variables accordingly. Is that possible?</p>
  
  <p>It would also be possible to add a new config variable and check it or something similar. But how can i access the config variable from the custom dialog?</p>
  
  <p>Thanks</p>