Created attachment 23381 [details]
Testcase for both plain Gtkmm and libglademm

I'm going to have to create a C example when I get around to this.
Feel free to do that for me.

Is that attachment a tar.gz? Please mention the filename when attaching.

I've been able to work around this problem by not deriving from
Gtk::OptionMenu or Gtk::MenuItem.  Instead, I've used SigC::bind to
call a method with an object as an argument, rather than storing the
object in a derived Gtk::MenuItem.

I've created a boost::lexical_cast<> workalike called

template<typename T>
std::string describe(const T& obj)

which converts the object into a textual description for use in the
optionmenu (it's specialised for each type).


How exactly should I write in a C testcase for this issue, given that
it only occurs when using C++ derived classes?

It's as though the set_menu method behaves differently depending on
wether you created the OptionMenu directly, or by libglademm
get_widget_derived.  The latter does have the menu (the item count is
correct), but it doesn't display them.

Thanks,
Roger

Sorry, but this is not a simple-as-possible test case. If you provide a simple
test case then I will investigate, and probably fix, any bug.

Is there any chance of us getting that test case?

What should the C testcase do?  There's no libglade get_widget_derived()
equivalent, so I'm unsure what exactly you want.  I'll be happy to try writing
another testcase--but I need to know what it should do first.

Thanks,
Roger

Nevermind about the C test case yet. We still don't have a simple C++ test case
from you.

Created attachment 33181 [details]
gtkmm-131566-2.tar.bz2

This testcase is a simplified version of the original testcase.  I've
 - removed all the templated code
 - removed all unused cruft
 - commented the objectoptionmenu header

The objectoptionmenu.* files implement the classes ObjectOptionMenuItem
(derived from Gtk::MenuItem) and ObjectOptionMenu (derived from
Gtk::OptionMenu).

examplewindow.* is plain C++, and just creates a main window containing an
ObjectOptionMenu containing some ObjectOptionMenuItems.  This works perfectly.

gladeexamplewindow.* is exactly the same, but the ObjectOptionMenu is got from
a Glade::XML object with get_widget_derived.  This appears to work according to
the debugging messages (the contained Gtk::Menu does contain the correct number
of items and the current selection is correct), but it shows up empty with
warnings:

OptionMenu::on_changed()
    There are 6 items
    Currently selected: 1
OptionMenu::on_changed()
    There are 6 items
    Currently selected: 5

(gladeexamplewindow:5036): Gtk-CRITICAL **: file gtkmenu.c: line 1235
(gtk_menu_popup): assertion `GTK_IS_MENU (menu)' failed

(gladeexamplewindow:5036): Gtk-CRITICAL **: file gtkmenu.c: line 1470
(gtk_menu_get_active): assertion `GTK_IS_MENU (menu)' failed


Hopefully this is a good bit simpler, but I don't think I can make it much
simpler without losing the purpose of what I'm trying to do.


Regards,
Roger

In your constructor

ObjectOptionMenu::ObjectOptionMenu(BaseObjectType* cobject,
				   const Glib::RefPtr<Gnome::Glade::Xml>& xml_interface):
  m_menu()
{}

You do not call the base class constructor.

This is explained here:
http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/ch19s03.html

Please reopen the bug if this does not fix the problem.

Also, I suggest that you use warnings as errors. This would have caught the
unused cobject parameter.

That does indeed fix the problem, thanks.

I thought it looked funny, but I couldn't for the life of me see what it
was--and I've written quite a few derived widgets with those constructors in. 
Sorry for being a such a lamer!

No problem. That's why I prod people to make test cases.