plams

require 'gtk2'

class Foo < Gtk::Container
        type_register
        def initialize
                super()
                set_flags Gtk::Widget::NO_WINDOW
        end
        def add child
                # !! following code generates this warning: "Gtk-WARNING **:GtkContainerClass::add not implemented for `Foo'"
                child.parent = self
        end
        def size_allocate
                # this method should be called by gtk subsystem, but it isn't
                puts "called size_allocate"
        end
        def size_request
                # this method also should be called by gtk subsystem, but it isn't
                puts "called size_request"
        end
end

class App < Gtk::Window
        def initialize
                super()
                foo = Foo.new

                button = Gtk::Button.new("hello")
                foo.add button

                add foo
        end
end

app = App.new
app.show_all
Gtk.main