Added HINT_UTILITY for Gtk::gdk_window_is_base This fixes some dragging issues in gimp.
Added HINT_UTILITY for Gtk::gdk_window_is_base
This fixes some dragging issues in gimp.

blue-shell/carbon-gtk,KDE/oxygen-gtk,blueshell-next/carbon-gtk,KDE/oxygen-gtk,blueshell-next/carbon-gtk,blue-shell/carbon-gtk