~/.gnucash and XDG default directories

[Geert Janssens]

Historically, GnuCash has always stored its user specific application data in 
~/.gnucash based on old linux (unix ?) conventions.

This didn't work really well on Mac OS X/Quartz, so John has overridden this 
path on OS X to make more sense there.

Now there's a bugreport that indicates this isn't the best place on Windows 
either [1].

I could override the path on Windows as well and be done with it, but in my 
investigation I found that even on linux ~/.<appname> is no longer the 
recommended place to store such information.

According to the XDG Base Directory Specification [2] the preferred location 
is ~/.local/share/<appname>.

The nice thing is, glib has a convenience function g_get_user_config_dir, 
which by default returns ~/.local/share on linux and the equivalent and proper 
~\Application Data (Windows XP) or ~\AppData\Roaming (Windows Vista/7).

I don't know what this routine returns on OS X, but I would expect it to 
return the proper location for user specific application data there as well. 
If not that should be reported as a bug againse glib on OS X.

In this light I would like to update the GnuCash code to make use of the 
g_get_user_data_dir function on all platforms and rename the directory from 
.gnucash to gnucash. That would give a better experience on all platforms IMO.
This is what the directories would become:
- Linux: ~/.local/share/gnucash
- Windows XP: c:\Documents and Settings\<user>\Application Data\gnucash
- Windows Vista/7: c:\Documents and Settings\<user>\AppData\Roaming\gnucash
- OS X: ?

I would obviously have to provide some conversion code as well, that would 
copy the old .gnucash contents to .local/share/gnucash to guarantee continuity 
for the users.

I also think this change may be better for 2.5/2.6 than 2.4.1.

Does anyone have any objections to this ?

Geert

[1] see https://bugzilla.gnome.org/show_bug.cgi?id=503722
[2] see http://standards.freedesktop.org/basedir-spec/basedir-spec-0.6.html