GNOME Bugzilla – Bug 668063
GtkWindow should support opacity of GdkWindow without effecting children GdkWindows
Last modified: 2018-02-10 03:28:45 UTC
Utility windows will occasionally want to have a mostly transparent background, with the exception of the widgets placed within the window. An example of this can be found in the PixelMator application. http://www.pixelmator.com/ I think this is a worthwhile feature to add to Gtk, either through some sort of "background-opacity" property, or CSS override.
We're moving to gitlab! As part of this move, we are closing bugs that haven't seen activity in more than 5 years. If this issue is still imporant to you and still relevant with GTK+ 3.22 or master, please consider creating a gitlab issue for it.