Crashing with widgets as class members

["John C. Spray" <spray lyx org>]

Hello,

I'm having crashes where I have widgets which created as members of a
class, rather than creating them with Gtk::manage(new Gtk::whatever).
This used to work okay, the code hasn't changed but the build options
may have done.

Am I doing something illegal when I do:

class MyClass {
	public:
	Gtk::ComboBoxText mycombo_;
}

Rather than

class MyClass {
	public:
	Gtk::ComboBoxText *mycombo_;
	void build();
}

void MyClass::build() {
	mycombo_ = Gtk::manage(new Gtk::ComboBoxText);
}

Because the latter seems to work where the first kind of thing gives
results like:

#0  IA__g_logv (log_domain=Variable "log_domain" is not available.
) at gmessages.c:503
#1  0x003f5963 in IA__g_log (log_domain=0x3ba01e "glibmm",
    log_level=G_LOG_LEVEL_ERROR,
    format=0x419d98 "file %s: line %d (%s): assertion failed: (%s)")
    at gmessages.c:517
#2  0x003f59b8 in IA__g_assert_warning (log_domain=0x3ba01e "glibmm",
    file=0x3baab7 "objectbase.cc", line=77,
    pretty_function=0x3ca180 "void
Glib::ObjectBase::initialize(GObject*)",
    expression=0x3baaa2 "gobject_ == castitem") at gmessages.c:552
#3  0x003afc1f in Glib::ObjectBase::initialize (this=Variable "this" is
not available.
) at objectbase.cc:77
#4  0x003af5ee in Object (this=0x9cf4070, __vtt_parm=0x898545c,
    construct_params= 0xbf8fa460) at object.cc:232
#5  0x0063585b in Object (this=0x9cf4038, __vtt_parm=0x8985458,
    construct_params= 0xbf8fa460) at object.cc:35
#6  0x00681f6b in Widget (this=0x9cf4038, __vtt_parm=0x8985454,
    construct_params= 0xbf8fa460) at widget.cc:5041
#7  0x006067d8 in Container (this=0x9cf4038, __vtt_parm=0x8985450,
    construct_params= 0xbf8fa460) at container.cc:674
#8  0x005ee074 in Bin (this=0x9cf4038, __vtt_parm=0x898544c,
    construct_params= 0xbf8fa460) at bin.cc:195
#9  0x00603d4b in ComboBox (this=0x9cf4038, __vtt_parm=0x8985448,
    construct_params= 0xbf8fa460) at combobox.cc:200
#10 0x006058ff in ComboBoxEntry (this=0x9cf4038, __vtt_parm=0x8985444)
    at comboboxentry.cc:141
#11 0x0069656f in ComboBoxEntryText (this=0x9cf4038) at
comboboxentrytext.cc:33
#12 0x086bd5da in lyx::frontend::GBibtex::GBibtex ()

Where GBibtex is a class with a member of type Gtk::ComboBoxEntry.

Regards,
John