Mike,

Warning shameless plug.

> Been to the mentioned sites. Good references. I've also been through the 
> xulnote tutorial. I'd like to write a financial application in XUL to 
> replace our Quickbooks (the only reason one of our computers is still 
> infested with MSWindows), so I need to learn how to interface XUL with 

If you want quickbooks for GNU\Linux I urge you too look at GNUCash
(http://www.gnucash.org)

> MySQL and to learn more about server/client relationships from the XUL 
> viewpoint. It'd be nice to have the XUL app on a central server rather 
> than as components of the client, but it's not critical - we have a 
> small network with only a few computers. I'll also have a PHP equivalent 

Originally we were going to write financials in XUL.  The problem is they
at the time and probably still do not handle external data very well.
They require basically XML datasources.  This is what prompted us to write
data aware XML markup for XPlatform forms with GNU Etnerprise.  You might
wisht to check it out http://www.gnue.org.  All forms are done in XML like
XUL, but you need to know no SQL or databinding to make data ware it
'automagically' binds for you.

BTW: Unless MySQL has fixed table level locking you DO NOT want to use
MySQL for financial applications.  Table level locking will KILL you even
in a small environment.  As any time your run complex reports you in
essence will be locking out your data entry team. Performance will be
horrible unless you do some replication scheme to make a reporting
'server'.  
 
> too, and maybe a Gnome equivalent as soon as development on Gnome_DB 
> matures... The database will be the same, so it doesn't matter what 
> client I write. I need to brainstorm on ways to abstract the database 
> functions so that I an use one library for all platforms - Gnome, PHP or 

GNU Enterprise does this.  Currently we support Oracle, DB2, PostGRES and
MySQL.

> XUL. It'd be nice to have the core application completely independent of 
> the interface so that any interface can be written to it.

This is concept of GNU Enterprise as well.  One form source will work on
Win32, Motif, GTK, Mac and soon WWW with no ifdefs etc..

BTW: Mozilla's XUL went down hill around M10 when Mike Shaver departed and
Dave Hyatt seemed to be less involved with data binding.  Most
unfortunate.  Plus the code was still so impossible to compile much less
code against at that time, we decided XUL wasnt best for us.

In its defense its still cool if you are wanting to just do XML data
sources.

Derek