RE: Tiny change to find-tag-default.

["Drew Adams" <drew.adams@oracle.com>]

    Suppose I'm looking at a text, and want to grep for a phrase
    (e.g. just two words) in that text, I highlight the text to search for
    (set mark, go to end of text) and do M-x lgrep. ...
    I don't think it makes sense to do this w/o transient-mark-mode,
    but that's why we have temporary transient-mark-mode marking.

That behavior ounds good to me. What about doing the same for `grep' and the
other similar commands?

OTOH, if done in `find-tag-default', this would also affect things like
function-called-at-point and variable-at-point. I don't know if that would
be a good feature or not.

[Not directly related - Is there a quick way to set the region around the
last occurrence found using isearch and query-replace (even if the latter is
exited with C-g)? If so, together with your proposal that would let you
immediately move from searching in a file to grepping for the same thing in
other files.]