Bug #66333 Crash when re-opening a routine

Description:
The attached instructions seem to show several problems, possibly related. 
1. When re-opening a routine, the new routine does not show up in the editor window.
2. After re-opening a model, opening a routine causes a crash.
3. After this crash, restarting workbench causes another crash.

----- Developer Notes -----

MySQL Workbench CE for Windows version 5.2.41  revision 9724
Configuration Directory: C:\Users\Luke\AppData\Roaming\MySQL\Workbench
Data Directory: C:\Program Files (x86)\MySQL\MySQL Workbench 5.2 CE
Cairo Version: 1.8.8
OS: Microsoft Windows 7 Home Premium Edition Service Pack 1 (build 7601), 64-bit
CPU: 4x Intel(R) Core(TM) i5-2410M CPU @ 2.30GHz, 4.0 GiB RAM
Active video adapter (0): Intel(R) HD Graphics 3000
Installed video RAM: 1795 MB
Current video mode: 1600 x 900 x 4294967296 colors
Used bit depth: 32
Driver version: 8.15.10.2761
Installed display drivers: igdumd64.dll,igd10umd64.dll,igd10umd64.dll,igdumd32,igd10umd32,igd10umd32
Current user language: English (United States)

Exception = System.InvalidCastException
Message = Unable to cast object of type 'MySQL.Forms.MenuItemImpl' to type 'MySQL.GUI.Workbench.Plugins.DockablePlugin'.
FullText = System.InvalidCastException: Unable to cast object of type 'MySQL.Forms.MenuItemImpl' to type 'MySQL.GUI.Workbench.Plugins.DockablePlugin'.
   at MySQL.GUI.Workbench.Plugins.DockablePlugin.GetFromFixedPtr(IntPtr ptr)
   at MySQL.GUI.Workbench.MainForm.ShowPlugin(IntPtr ptr)
   at MySQL.Forms.AppImpl.show_editor_wrapper(UInt32 native_handle)
   at boost.detail.function.void_function_invoker1<void (__cdecl*)(unsigned int),void,unsigned int>.invoke(function_buffer* function_ptr, UInt32 a0)
   at MySQL.Grt.ListModel.activate_node(NodeId node)
   at MySQL.GUI.Workbench.ModelOverviewForm.listViewDoubleClick(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnDoubleClick(EventArgs e)
   at System.Windows.Forms.ListView.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

How to repeat:
Open a model containing two routines, A and B
Double-click routine A
Double-click routine B
Double-click routine A
>> Sign of trouble: description editor now shows routine A, while routine window still shows routine B
Close the model
Re-open the model
Double-click routine B
>> Crash!
Exit workbench
Re-open workbench immediately
>> Crash!

Duplicate of bug #66013