[gtkmm] adding a widget to a container

[cedric <cedric probesys com>]

Hello,
i m sorry to ask for help again and again, but i ve a PARANORMAL 
(yes...) error!!!

in one of my class constructors, i ve created a toolbar which i want to 
add to a Gtk::HBox.
the toolbar is declared as "Gtk::Toolbar toolbarmod;" in my testmodule.hh.

in the constructor of testmodule.cc:

...

Gtk::HBox a;    a.add(toolbarmod);
//it works, normal

Gtk::HBox *b;    b->add(toolbarmod);
// provoques a seg fault !?!?!

Gtk::HBox *c;    (*c).add(toolbarmod);
// provoques a seg fault !?!?!

...

i ve no compilation error with both of these instructions!
but when i execute them, it s ok with the first one, but i have a 
segfault (symbol toolbarmod undefined) with the second and the third 
ones. it don t underdstand: it should work with none or all of them, but 
not just some of them since it s the same thing!
i ve put some cout<< fooX <<endl before and after these instructions, so 
i m sure that it s the instruction itself which provoques the seg fault, 
so it s not because of the temporary a,b,c variables which are deleted. 
initially i worked with a global ptr instead of a,b,c.

if you have any explanation, i really would like you to tell me! ;-)
grateful thanks!

cedric