We used to always make the labels in message dialogs selectable,
which is a bit problematic wrt. to keynav - the label can
unexpectedly 'turn blue', which irritates some people.
With the new gtk-keynav-use-caret setting, we can now only
make the labels selectable when it is required for accessibilty
reasons.
This subdirectory gets in the way when integrating the inspector
build more fully with GTK+, and does not really add anything.
Just move everything one level up.