These flags serve two purposes. First, the application can call the function gtk-places-sidebar-open-flags using these flags as a bitmask. This tells the sidebar that the application is able to open folders selected from the sidebar in various ways, for example, in new tabs or in new windows in addition to the normal mode.

Second, when one of these values gets passed back to the application in the "open-location" signal, it means that the application should open the selected location in the normal way, in a new tab, or in a new window. The sidebar takes care of determining the desired way to open the location, based on the modifier keys that the user is pressing at the time the selection is made.

If the application never calls the function gtk-places-sidebar-open-flags, then the sidebar will only use :normal in the "open-location" signal. This is the default mode of operation.

(define-g-flags "GtkPlacesOpenFlags" gtk-places-open-flags
  (:export t
   :type-initializer "gtk_places_open_flags_get_type")
  (:normal     #.(ash 1 0))
  (:new-tab    #.(ash 1 1))
  (:new-window #.(ash 1 2)))  

:normal

This is the default mode that gtk-places-sidebar uses if no other flags are specified. It indicates that the calling application should open the selected location in the normal way, for example, in the folder view beside the sidebar.

:new-tab

When passed to the function gtk-places-sidebar-open-flags, this indicates that the application can open folders selected from the sidebar in new tabs. This value will be passed to the "open-location" signal when the user selects that a location be opened in a new tab instead of in the standard fashion.

:new-window

Similar to :new-tab, but indicates that the application can open folders in new windows.