Well, I'm a "edit the config by hand" kind of guy, so I decided I'd
refine my filters quickly using my favorite editor on
~/evolution/filters.xml instead of bothering with the click, wait,
click, wait that is associated with a GUI process like that.  So, I do
some rearranging/alteration to the best of my ability (with the
information that I have), and save a copy of my old filters just in
case.  Well, when I run Evolution, apparently it doesn't parse my XML
well, so it simply clobbers the filters.xml file - no explanation of
where it had trouble parsing, no back up of the file (fortunately I had
one).  There is no error message warning about this either on the
command line (stdout/stderr) or via a GNOME dialog.

At the very least, I think the overwriting of a file like that simply by
invoking the program needs to be noted in a warning dialog.  It'd be
really nice if it could print a more diagnostic message than just "oops,
had to clobber filters.xml" as well.