This dialog appears when the "Add or Remove Model Add-in" menu item is chosen from the diagrams context menu.
It lists all of the add-in components currently known on the system. Each item has a check box to its left that indicates whether the model already has such an add-in active for it.
To load an add-in, just click in the check box.
To unload an add-in, clear the check box and use OK
Use OK to complete the operation.
The Browse button on the dialog will activate a standard file explorer dialog. Navigate to a DLL that you know contains valid MSBNx add-in automation objects and open the file.
All of the add-in objects available in the binary library will be added to the list, and you will then be able to activate one or more of them for the current diagram.