Fix float parsing error (bug #16295)

Signed-off-by: Sean Davis <smd.seandavis@gmail.com>

src/xfce4-screensaver-configure

@@ -80,7 +80,7 @@ class XfconfChannel:
         return self._set_property("bool", prop, value)
 
     def get_double(self, prop, default):
-        return float(self._get_property(prop, default))
+        return locale.atof(self._get_property(prop, default))
 
     def set_double(self, prop, value):
         return self._set_property("double", prop, value)