Locations are the last big part of the application that can't be tied to companies.
This can be a problem with FullMultipleCompanySupport, because you can't restrict the visibility of locations to the company of the users.
In order to change this, add a company_id to the locations table and wire everything up in the views and controllers.
Aditionally add a new formatter to filter the locations to a specific company, like it is done for assets.
Locations are properly scoped to the users company if FullMultipleCompanySupport is enabled.
If a parent location of a location has a different company than the user, the location does not show up.