/// <summary>
 /// Retrieves the content by persist string
 /// </summary>
 public static DockContent GetContentFromPersistString(String persistString)
 {
     for (Int32 i = 0; i < PluginPanels.Count; i++)
     {
         DockContent pluginPanel = PluginPanels[i];
         if (pluginPanel.GetPersistString() == persistString)
         {
             RestoredPlugins.Add(pluginPanel.GetPersistString());
             return(pluginPanel);
         }
     }
     return(null);
 }