Wt

See attached example which uses WItemDelegate.

It uses a WTimer to call the updateData() function.

This emits the dataChanged signal for index(0,0) every second.

This should simulate the underlying data changing.

If you start editing index(0,0) using the delegate then the program segfaults.

Thread 2 (Thread 1374):
#0  std::_Rb_tree<std::string, std::pair<std::string const, Wt::WString>, std::_Select1st<std::pair<std::string const, Wt::WString> >, std::less<std::string>, std::allocator<std::pair<std::string const, Wt::WString> > >::find (this=0x0, __k="drop") at /usr/include/c++/4.9.2/bits/stl_tree.h:1913
#1  0xb6d22a20 in find (__x=..., this=<optimized out>) at /usr/include/c++/4.9.2/bits/stl_map.h:860
#2  Wt::WWebWidget::attributeValue (this=0xb4d52f40, name=...) at /usr/src/debug/wt/3.3.4-3/git/src/Wt/WWebWidget.C:882
#3  0xb6c0a688 in Wt::WItemDelegate::update (this=<optimized out>, widget=<optimized out>, index=..., flags=<error reading variable: Cannot access memory at address 0x0>) at /usr/src/debug/wt/3.3.4-3/git/src/Wt/WItemDelegate.C:204

#4  0xb6ccc3a0 in Wt::WTableView::renderWidget (this=this@entry=0xb4ca0fa8, widget=widget@entry=0xb4d52f40, index=...) at /usr/src/debug/wt/3.3.4-3/git/src/Wt/WTableView.C:281
#5  0xb6ccffac in Wt::WTableView::updateItem (this=this@entry=0xb4ca0fa8, index=..., renderedRow=renderedRow@entry=3, renderedColumn=renderedColumn@entry=1) at /usr/src/debug/wt/3.3.4-3/git/src/Wt/WTableView.C:1461
#6  0xb6cd023c in Wt::WTableView::modelDataChanged (this=0xb4ca0fa8, topLeft=..., bottomRight=...) at /usr/src/debug/wt/3.3.4-3/git/src/Wt/WTableView.C:1439

#7  0xb6cd4b2c in operator() (a2=..., a1=..., p=<optimized out>, this=<optimized out>) at /usr/include/boost/bind/mem_fn_template.hpp:280
#8  operator()<boost::_mfi::mf2<void, Wt::WTableView, const Wt::WModelIndex&, const Wt::WModelIndex&>, boost::_bi::list6<Wt::WModelIndex&, Wt::WModelIndex&, Wt::NoClass&, Wt::NoClass&, Wt::NoClass&, Wt::NoClass&> > (a=<synthetic pointer>, f=..., this=<optimized out>) at /usr/include/boost/bind/bind.hpp:392
#9  operator()<Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass> (a3=<synthetic pointer>, a4=<synthetic pointer>, a5=<synthetic pointer>, a6=<synthetic pointer>, a2=..., a1=..., this=<optimized out>) at /usr/include/boost/bind/bind_template.hpp:203
#10 boost::detail::function::void_function_obj_invoker6<boost::_bi::bind_t<void, boost::_mfi::mf2<void, Wt::WTableView, Wt::WModelIndex const&, Wt::WModelIndex const&>, boost::_bi::list3<boost::_bi::value<Wt::WTableView*>, boost::arg<1>, boost::arg<2> > >, void, Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass>::invoke (function_obj_ptr=..., a0=..., a1=..., a2=..., a3=..., a4=..., a5=...) at /usr/include/boost/function/function_template.hpp:153
#11 0x000995a0 in operator() (a1=..., a0=..., this=0xb4ca7404, a2=..., a3=..., a4=..., a5=...) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/function/function_template.hpp:767
#12 m_invoke<boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)>, 0u, 1u, 2u, 3u, 4u, 5u, Wt::WModelIndex&, Wt::WModelIndex&, Wt::NoClass&, Wt::NoClass&, Wt::NoClass&, Wt::NoClass&> (args=..., func=..., this=<optimized out>) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/detail/variadic_slot_invoker.hpp:92
#13 operator()<boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)>, Wt::WModelIndex&, Wt::WModelIndex&, Wt::NoClass&, Wt::NoClass&, Wt::NoClass&, Wt::NoClass&, 6u> (args=..., func=..., this=<optimized out>) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/detail/variadic_slot_invoker.hpp:81
#14 m_invoke<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)> >, boost::signals2::mutex> > > (connectionBody=..., this=0xb4bfc1f0) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/detail/variadic_slot_invoker.hpp:127
#15 operator()<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)> >, boost::signals2::mutex> > > (connectionBody=..., this=0xb4bfc1f0) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/detail/variadic_slot_invoker.hpp:120
#16 dereference (this=0xb4bfc128) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/detail/slot_call_iterator.hpp:82
#17 dereference<boost::signals2::detail::slot_call_iterator_t<boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type, Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass>, std::_List_iterator<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)> >, boost::signals2::mutex> > >, boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)> >, boost::signals2::mutex> > > (f=...) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/iterator/iterator_facade.hpp:540
#18 operator* (this=0xb4bfc128) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/iterator/iterator_facade.hpp:646
#19 operator()<boost::signals2::detail::slot_call_iterator_t<boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type, Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass>, std::_List_iterator<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)> >, boost::signals2::mutex> > >, boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)> >, boost::signals2::mutex> > > (last=..., first=..., this=<optimized out>) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/optional_last_value.hpp:55
#20 operator()<boost::signals2::optional_last_value<void>, boost::signals2::detail::slot_call_iterator_t<boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type, Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass>, std::_List_iterator<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)> >, boost::signals2::mutex> > >, boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::function<void(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)> >, boost::signals2::mutex> > > (last=..., first=..., combiner=..., this=<optimized out>) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/detail/result_type_wrapper.hpp:64
#21 boost::signals2::detail::signal_impl<void (Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass), boost::signals2::optional_last_value<void>, int, std::less<int>, boost::function<void (Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)>, boost::function<void (boost::signals2::connection const&, Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass)>, boost::signals2::mutex>::operator()(Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass) (this=0x1b00, this@entry=0xb4ca5df0, args#0=..., args#1=..., args#2=args#2@entry=..., args#3=args#3@entry=..., args#4=args#4@entry=..., args#5=args#5@entry=...) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/detail/signal_template.hpp:246
#22 0x000947bc in operator() (args#1=..., args#0=..., this=<optimized out>, args#2=..., args#3=..., args#4=..., args#5=...) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/boost/signals2/detail/signal_template.hpp:718
#23 Wt::Signal<Wt::WModelIndex, Wt::WModelIndex, Wt::NoClass, Wt::NoClass, Wt::NoClass, Wt::NoClass>::emit (this=this@entry=0xb4ca0b28, a1=..., a2=..., a3=..., a4=..., a5=..., a6=...) at /opt/poky/1.8/sysroots/cortexa8hf-vfp-neon-poky-linux-gnueabi/usr/include/Wt/WSignal:992
#24 0x000957d4 in SimulateMenuModel::updateData (this=<optimized out>) at src/GuiModels.cpp:2708