is a variable defined in `
Its value is
- Automatically becomes buffer-local when set.
- This variable may be risky if used as a file-local variable.
If non-nil, a list of functions called just before context (or
other non-change) fontification is done. Typically they will
extend the region.
These functions will be run in the order given. Each of them
takes 2 parameters, the BEG and END of the region to be
fontified. Point is undefined on both entry and exit. On entry,
the buffer will have been widened and match-data will have been
saved; the return value is a cons of the adjusted
region, (NEW-BEG . NEW-END).