This patch was applied on 8/23/2006. It’s included in tcsh versions 6.14.06 and later.

For the impatient:
Patch for tcsh 6.14.00

I use tcsh as my shell, and I love it. This patch adds to tcsh’s usability by highlighting some regions in reverse video.

Specifically, it highlights the match during incremental search, and in emacs mode, the region between the mark and cursor. Highlighting is off by default; it can be turned on by setting the shell variable highlight.

Here’s a screenshot while the mark is set:

…and an incremental search screenshot:

The patch applies cleanly against tcsh 6.14.00. See the discussion on the tcsh list for more details.