reftex-refontify-context

reftex-refontify-context is a variable defined in `reftex-vars.el'.
Its value is

1

Documentation:
Non-nil means, re-fontify the context in the label menu with font-lock.
This slightly slows down the creation of the label menu. It is only necessary
when you definitely want the context fontified.

This option may have 3 different values:
nil Never refontify.
t Always refontify.
1 Refontify when absolutely necessary, e.g. when old versions of X-Symbol.
The option is ignored when `reftex-use-fonts' is nil.

You can customize this variable.