Currently if you open a file that does not belong to the active configuration it displays a message with very limited options and may be confusing to newer users, my suggestion to solve this is as follows.

If you try to open a file that has an assigned configuration other than the last used or currently selected configuration, pop a dialog with the Workspaces and Worksets listed in combobox options listing all available configurations the same as on the startup screen, for the user to select the correct one.