What constitutes "user configuration files" in the XDG basedir spec?

[Rodney Dawes]

On Sat, 2009-01-10 at 22:09 +0100, Dieter Plaetinck wrote:
> Hi all,
> at http://standards.freedesktop.org/basedir-spec/basedir-spec-0.6.html 
> it is explained that $XDG_DATA_{HOME,DIRS} is for "(user specific) data 
> files" and $XDG_CONFIG_{HOME,DIRS} for "(user specific) configuration 
> files".
> However, it is not exactly explained what each mean.
> 
> Specifically, afaik everything that goes into $XDG_CONFIG_HOME should be 
> controlled by the user himself, eg any update of files in this directory 
> is the result of:
> - the user updating the file himself manually.
> - the file being updated because the user changed one or more settings 
> in a GUI panel.
> 
> Eg: Isn't it wrong for software to update files in $XDG_CONFIG_HOME (and 
> by extension $XDG_CONFIG_DIRS) around the users back?
> I've seen many programs who store things like "last window position", 
> "last 10 opened items" etc in $XDG_CONFIG_HOME.  I don't think this is 
> what $XDG_CONFIG_HOME is for (I think this belongs in the user data 
> category), but then again, I couldn't find this being defined in the spec.
> 
> Do you agree with this point of view?
> If so, I would be happy to contribute an updated version of the spec 
> based on the above wordings.

If I resize my app's window to be more suitable for my uses, where
should that configuration be saved then? It is configuration data,
though all configuration data may not necessarily be what you expect
it to be.