Customizations in DGN Libraries
Custom tools, toolboxes, tasks, workflows, main tasks, and context menu customizations are created and stored in DGN libraries . This allows administrators to customize them in one place and to distribute the customizations to many users.
When you open or create a DGN file you can see and use all the customizations in the configured DGN libraries. If you create custom tools, toolboxes, tasks, workflows, main tasks, or context menu customizations and do not want to make them available to others, you should save them in a "personal" DGN library.
If the open DGN file is not a configured DGN library, you cannot use the features on the Tools tab in the Customize dialog while that DGN file is open. The configuration variable MS_GUIDGNLIBLIST (set by default to point to MS_DGNLIBLIST and to the DGN libraries in the active interface component's folder) and the configuration variable _USTN_SYSTEM_GUIDGNLIBLIST specify which files can be used for customizations.
If the open DGN file is not a configured DGN library and you want to use the features on the Tools tab, you can open a configured DGN library from the Customize dialog.