app chooser widget: protect against show_all
app chooser widget: protect against show_all

The visibility of the 'no apps' placeholder is managed by
the dialog, it should not be affected by gtk_widget_show_all.

https://bugzilla.gnome.org/show_bug.cgi?id=748080

jadahl/gtk,alexlarsson/gtk,jadahl/gtk,jadahl/gtk,grubersjoe/adwaita,alexlarsson/gtk,alexlarsson/gtk,jadahl/gtk,jadahl/gtk,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,alexlarsson/gtk,grubersjoe/adwaita,jadahl/gtk,grubersjoe/adwaita,alexlarsson/gtk,jadahl/gtk,jadahl/gtk,alexlarsson/gtk