I know that if an xref changes while a host drawing is open, AutoCAD will notify the user that the xref has changed and they can quickly reload it from the notification or from the xref manager. I also know that it will automatically be updated the next time the host drawing is opened.
I have a user that just asked me whether the xref could automatically update while she's in the host drawing, rather than just notify her (maybe on the next regen or save, kind of like fields do). I know that AutoCAD does not currently do this, but I want to be able to give her a good explanation of why. Any takers?