inspector: Show hidden windows in the inspector
inspector: Show hidden windows in the inspector

This allows us to access otherwise hidden windows, which can be
useful to provide better debug information than would be available
through other means.

https://bugzilla.gnome.org/show_bug.cgi?id=736557

alexlarsson/gtk,Adamovskiy/gtk,jessevdk/gtk,davidgumberg/gtk,jigpu/gtk,jadahl/gtk,grubersjoe/adwaita,alexlarsson/gtk,alexlarsson/gtk,Adamovskiy/gtk,ahodesuka/gtk,grubersjoe/adwaita,chergert/gtk,jadahl/gtk,grubersjoe/adwaita,ahodesuka/gtk,alexlarsson/gtk,Adamovskiy/gtk,chergert/gtk,grubersjoe/adwaita,davidgumberg/gtk,Adamovskiy/gtk,davidgumberg/gtk,grubersjoe/adwaita,grubersjoe/adwaita,Lyude/gtk-,alexlarsson/gtk,Adamovskiy/gtk,ahodesuka/gtk,Lyude/gtk-,davidgumberg/gtk,ahodesuka/gtk,alexlarsson/gtk,jadahl/gtk,jigpu/gtk,jigpu/gtk,jessevdk/gtk,jadahl/gtk,grubersjoe/adwaita,davidgumberg/gtk,jessevdk/gtk,jessevdk/gtk,jadahl/gtk,jessevdk/gtk,ahodesuka/gtk,davidgumberg/gtk,alexlarsson/gtk,jessevdk/gtk,jigpu/gtk,alexlarsson/gtk,Lyude/gtk-,davidgumberg/gtk,jigpu/gtk,jadahl/gtk,jigpu/gtk,Lyude/gtk-,grubersjoe/adwaita,Adamovskiy/gtk,Lyude/gtk-,Lyude/gtk-,Adamovskiy/gtk,chergert/gtk,Lyude/gtk-,jadahl/gtk,Lyude/gtk-,chergert/gtk,ahodesuka/gtk,jigpu/gtk,ahodesuka/gtk,jigpu/gtk,Adamovskiy/gtk,jessevdk/gtk,davidgumberg/gtk,ahodesuka/gtk,chergert/gtk,jadahl/gtk,chergert/gtk,chergert/gtk,chergert/gtk