Possible bug?

[Omar Barneto <obarneto hasar com>]

I think I've found a bug. I am not sure if it comes from gtkmm or gtk
This bug can be reproduced with this test program:

#include <gtkmm/main.h>
#include <gtkmm/window.h>
#include <gtkmm/button.h>
#include <gtkmm/label.h>

class MainWindow : public Gtk::Window
{
public:
MainWindow() : Gtk::Window(Gtk::WINDOW_TOPLEVEL)
{
   add(boton);
   boton.add(label);
   set_size_request(100,100);
   boton.signal_clicked().connect(sigc::mem_fun(*this, 
&MainWindow::Click));
   show_all();
}
void Click()
{
   boton.set_sensitive(false);
   label.set_markup("<span  foreground=\"black\">234</span>");
}
private:
   Gtk::Button boton;
   Gtk::Label label;
};
int main (int argc, char *argv[])
{
   Gtk::Main kit(argc, argv);

   MainWindow m();
   Gtk::Main::run(m);
   return 0;
}

When I click the button the program prints at console "Illegal 
instruction"  and aborts.
That happened only if I put the button "insensitive" and set the 
foreground property with set_markup.
If I put the button "sensitive" or not set the background property the 
program works OK.
I run this program over a "Linux Fedora4 2.6.11-1.1369_FC4"

The command line to compile the program is:
g++ -o prueba prueba.o -L/usr/local/lib -lgtkmm-2.4 -lgdkmm-2.4 
-latkmm-1.6 -lgtk-x11-2.0 -lpangomm-1.4 -lglibmm-2.4 -lsigc-2.0 
-lgdk-x11-2.0 -latk-1.0 -lgdk_pixbuf-2.0 -lm -lpangocairo-1.0 
-lpango-1.0 -lcairo -lgobject-2.0 -lgmodule-2.0 -ldl -lglib-2.0 
-L/usr/local/lib -lsigc-2.0
g++ -o prueba prueba.o -L/usr/local/lib -lgtkmm-2.4 -lgdkmm-2.4 
-latkmm-1.6 -lgtk-x11-2.0 -lpangomm-1.4 -lglibmm-2.4 -lsigc-2.0 
-lgdk-x11-2.0 -latk-1.0 -lgdk_pixbuf-2.0 -lm -lpangocairo-1.0 
-lpango-1.0 -lcairo -lgobject-2.0 -lgmodule-2.0 -ldl -lglib-2.0 
-L/usr/local/lib -lsigc-2.0