x utility for window information

[John Russell]

Guys, we talked about this several months ago.  What is the name of
the X utility that you can click on a window and it tells you about
the window?  Its not xwininfo, this one had way more information, like
what CLASS the window was in and all the atoms that were set.  I can't
even come up with a good google search, all I get is xdpyinfo.  Does
anyone remember? Thanks.

John