For an infinitesimal amount of time after opening the options dialog, a
spinner is displayed at the start of the action area while the dialog
loads asynchronously. Display the spinner in the center of the dialog
instead, using a GtkStack to switch between spinner mode and normal
mode. Test by removing the calls to printer_get_ppd_async(),
get_named_dest_async(), and get_ipp_attributes_async() from the bottom
of populate_options().
Why? (1) It looks better this way. (2) Need to stop using the action
area in order to switch to a header bar.
https://bugzilla.gnome.org/show_bug.cgi?id=755713https://bugzilla.gnome.org/show_bug.cgi?id=779708
Add Options dialog which allows users to set more options than current dialog.
The dialog reads printer's PPD file and add its options to the dialog together
with some preselected IPP options (#678637).
All operations in the dialog are asynchronous.
During implementation of this, the option for setting allowed users was removed
because this is not suitable for this panel (the option is intended for
administrators).
