Errors when preview image functions aren't the same from user to user

[stevevanhooser]

If a user makes a preview image with a preview image function on their local machine, and then opens on another machine that doesn't have that same named instance of the preview image function, then there is an error.

[stevevanhooser]

What are possible solutions?

The problem is that the short name of the preview image function refers to an entity on the user's local computer.

Possible solutions:

Never re-do the calculation once it is done unless the user clicks a "recalculate" button. Would need to add a button that says "re-calculate preview image". But a button on the panel that indicates if the preview image function parameters that are "current" are different from those of the currently viewed ('*' or not). Under this model, the preview image function menu would need to change to list all of the current preview functions PLUS any that were already calculated on disk.

When we encounter a preview image function with a short name that is not in our system, import it? OK except one condition: What if 2 people have preview image functions with short names that are identical but the parameters are not? Well, then, don't import.

OK, it would seem that

1. importing any unknown function, plus
2. only recalculating on command

will solve the problem.

When should we check for imports? Whenever we switch to view a new directory, yes?