find-grep-dired - default directory to start with

[Martin Barth <martin@senfdax.de>]

Hello,

i've just discovered the function find-grep-dired which turns out to be
very useful for me.
When you invoke M x find-grep-dired you get asked for the starting
directory.

I am looking for a alternatetive function where this "Start directory"
can be predefined.
basically

(setq my-default-search-dir '/home/foo/bar);

and then M-x find-grep-dired-in-my-default-search-dir

Any Ideas?

Thank You
Martin!