gpe-confd is actively maintained and stable for daily use.
The source code can be found in SVN, module base/gpe-confd.
Distributions known to ship gpe-confd are:
gpe-confd is distributed under the GPL.
gpe-confd retrieves settings from the X server and stores them in a SQLite database. The settings from the database are restored to the X server whenever gpe-confd is launched. Setting changes are saved in the database automatically without that the process that makes the setting needs to be aware of this. Deleted Xsetting values are deleted from the database as well.
The command line tool xst can be used to display and modify Xsetting values.