Sets the sidebar position for self.
If it's set to gtk.types.PackType.Start, the sidebar is displayed before the content, if gtk.types.PackType.End, it's displayed after the content.
the new position
Sets the sidebar position for self.
If it's set to gtk.types.PackType.Start, the sidebar is displayed before the content, if gtk.types.PackType.End, it's displayed after the content.