Question about interpretation of XDG_DATA_DIRS

[Jan D.]

Hello.

I'm new here so please excuse me if this is the wrong place to ask.
When reading the XDG Base Directory Specification (0.6), it says:

"If $XDG_DATA_DIRS is either not set or empty, a value equal to 
/usr/local/share/:/usr/share/ should be used."

and

"If $XDG_CONFIG_DIRS is either not set or empty, a value equal to 
/etc/xdg should be used."

Case in point is Gtk+ 2.6 that looks for the default theme file only in 
/usr/local/share and /usr/share if XDG_DATA_DIRS is not set.  But as I 
have several different installations of Gtk+ (and other things), I 
would expect them to also search $datadir (or $prefix/share).  They 
refer to the default-theme-specification, which I have not been able to 
locate, but I suspect that it references the "Base Directory 
Specification".

Later on in the specification it does say:

"Other specifications may reference this specification by specifying 
the location of a data file as $XDG_DATA_DIRS/subdir/filename. This 
implies that:

     * Such file should be installed to $datadir/subdir/filename with 
$datadir defaulting to /usr/share."


So is it the intention of the specification that packages like Gtk+ 
shall search $datadir or is it just /usr/local/share:/usr/share?

Personally I would want the default for XDG_CONFIG_DIRS to be 
$datadir:/usr/local/share:/usr/share.  Without that, installing 
different versions with different $prefix becomes impossible.

Thanks,

	Jan D.