Isearch overlay priority

[Juri Linkov]

Currently the isearch string in ediff-processed buffers is not
highlighted on diff regions, because ediff overlays have higher
priority than isearch overlays.  The ability to highlight the current
search string is one of the main features of isearch, and due to the
transient nature of isearch overlays (they are removed as soon as
isearch exits), I think isearch should take precedence over highlighting
of underlying ediff regions.

ediff overlays have priorities starting from 100, and isearch overlay
currently has priority 1 and isearch lazy-highlight overlays have
priority 0.  Increasing isearch overlay priority to 1001, and
lazy-highlight overlay priority to 1000 will highlight isearch strings
over ediff regions.  Should we add an option for isearch overlay priority?
For instance, `show-paren-priority' has one:

(defcustom show-paren-priority 1000
  "*Priority of paren highlighting overlays."
  :type 'integer
  :group 'paren-showing
  :version "21.1")

But really I doubt that isearch overlay priorities 1000 and 1001
will cause any problems, and no one might want to decrease them.

-- 
Juri Linkov
http://www.jurta.org/emacs/