GTK3 window transparent

Question

Is there a way or a hack to create a GTK+3 transparent window without a composition manager in Linux? I want a GtkWindow invisible (zero alpha) with visible childs objects. I've triedgtk_widget_set_opacity(window, 0.0); and another things but it didn't work.

I'm using Arch Linux with OpenBox. Sorry for my english.

EDIT

I've created my window with GDK_WINDOW_TYPE_HINT_DESKTOP flag so my window will be always on desktop, and i think the way to do what i want is get desktop wallpaper and draw my window background with this image. It is possible to do this?

Answer 1

it worked well for me, with a compositing manager (xcompmgr or picom) and initializing window with

  GdkScreen *screen;
  GdkVisual *visual;

  gtk_widget_set_app_paintable(win, TRUE);
  screen = gdk_screen_get_default();
  visual = gdk_screen_get_rgba_visual(screen);

  if (visual != NULL && gdk_screen_is_composited(screen)) {
    gtk_widget_set_visual(win, visual);
  }