Create a new GNOME application status bar. If has_progress is TRUE,
a small progress bar widget will be created, and placed on the left
side of the appbar. If has_status is TRUE, a status bar, possibly
an editable one, is created.
interactivity determines whether the appbar is an interactive
"minibuffer" or just a status bar. If it is set to
Gnome.PREFERENCES_NEVER, it is never interactive. If it is set to
Gnome.PREFERENCES_USER we respect user preferences from
ui-properties. If it's Gnome.PREFERENCES_ALWAYS we are interactive
whether the user likes it or not. Basically, if your app supports
both interactive and not (for example, if you use the
gnome-app-util interfaces), you should use
Gnome.PREFERENCES_USER. Otherwise, use the setting you
support. Please note that "interactive" mode is not functional now;
GtkEntry is inadequate and so a custom widget will be written eventually.