Comment 2 for bug 809009

StacktraceTop:
 g_return_if_fail_warning (log_domain=0x14b5cbb "Gtk", pretty_function=0x157ef40 "IA__gtk_widget_style_get", expression=0x14b7cd6 "GTK_IS_WIDGET (widget)") at /build/buildd/glib2.0-2.29.10/./glib/gmessages.c:582
 IA__gtk_widget_style_get (widget=0x0, first_property_name=0x71f187d "trough-border") at /build/buildd/gtk+2.0-2.24.5/gtk/gtkwidget.c:10015
 QGtkStyle::pixelMetric (this=0xa5d90b8, metric=QStyle::PM_ScrollBarExtent, option=0xbfa67050, widget=0xa71a2c8) at styles/qgtkstyle.cpp:528
 QScrollBar::sizeHint (this=0xa71a2c8) at widgets/qscrollbar.cpp:494
 QAbstractScrollAreaPrivate::layoutChildren (this=0xa737f00) at widgets/qabstractscrollarea.cpp:355