#845 XSettings changes do not always stick

[Yaakov Selkowitz]

With lxsession git master (2016-11-27), I have noticed a situation where XSettings changed during a session do not "stick":

1) Run lxappearance and change the widget theme noticably (e.g. from Adwaita to BlackMATE), and Apply. All GTK+ windows will retheme themselves after a few seconds.
2) Start lxsession-default-apps and change any default app.

Boom! Windows then regress to the original theme rather than the one just selected.