Re: custom: how do I augment an option?

[Stefan Monnier]

> So, what is the official method?

There are 3 official methods:
1- forget about flexibility and just set the var to a constant value
   that does not depend on the default value.  That can be done from the GUI.
2- if you want to use actual code (instead of a mere constant), then
   don't use Customize, and use something like the add-hook code you showed.
3- submit a patch for Customize which lets the user specify not just
   a new value but a change (like a "diff") to the default value.
   For lists representing sets, a way for the user to specify elements
   to add and elements to remove would be great.  For lists where order
   matters, the user should additionally have some control over where to
   add elements.
Point 3 would be *really* welcome.

        Stefan