[pygtk] set_use_markup and gtk.Button

[Art Hunkins]

I have been happily using the set_use_markup property of gtk.Label and 
gtk.Frame with XML markup, to create bolded, italic and various sized text.

I need to do this with gtk.Button as well - to do the same with (callback) 
button labels. However, I've not been able. I've employed the two general 
approaches below (with results immediately below them):

#1:

def cbbutton(self,box,callback,title=""):
 """Creates a callbackbutton
 box: parent box
 callback: click callback
 title: if given, the button name
 returns the widget instance"""
 self.cbbutts = self.cbbutts + 1
 label = gtk.Label(title)
 label.set_use_markup(True)
 butt = gtk.Button(" %s " % label)
 box.pack_start(butt, False, False, 5)
 self.cbbuttons.append([butt,label,0])
 butt.connect("clicked", callback)
 butt.show()
 return butt

The above version runs fine, but gives unwanted button labels, of this 
variety:
<gtk.Label object a 0x[....] (GtkLabel at 0x[....different])>


#2:

def cbbutton(self,box,callback,title=""):
 """Creates a callbackbutton
 box: parent box
 callback: click callback
 title: if given, the button name
 returns the widget instance"""
 self.cbbutts = self.cbbutts + 1
 label = gtk.Label()
 label.set_markup(title)
 butt = gtk.Button()
 butt.child = label
 label.show()
 box.pack_start(butt, False, False, 5)
 self.cbbuttons.append([butt,label,0])
 butt.connect("clicked", callback)
 butt.show()
 return butt

The above version crashes, with the following error log:

/usr/lib/python2.6/site-packages/sugar/activity/main.py:35: GtkWarning:
gtk_widget_realize: assertion `GTK_WIDGET_ANCHORED (widget) ||
GTK_IS_INVISIBLE (widget)' failed
activity.show()
Gtk:ERROR:gtkwidget.c:7967:gtk_widget_real_map: assertion failed:
(GTK_WIDGET_REALIZED (widget))

Can someone please suggest what changes might give me a proper label?

FWIW, including XML tags in "title" makes no difference whatever in the 
above results.

Art Hunkins