reftex-highlight-selection

reftex-highlight-selection is a variable defined in `reftex-vars.el'.
Its value is

cursor

Documentation:
Non-nil mean, highlight selected text in selection and *toc* buffers.
Normally, the text near the cursor is the selected text, and it is
highlighted. This is the entry most keys in the selection and *toc*
buffers act on. However, if you mainly use the mouse to select an
item, you may find it nice to have mouse-triggered highlighting
instead or as well. The variable may have one of these values:

nil No highlighting.
cursor Highlighting is cursor driven.
mouse Highlighting is mouse driven.
both Both cursor and mouse trigger highlighting.

Changing this variable requires to rebuild the selection and *toc* buffers
to become effective (keys `g' or `r').

You can customize this variable.