Wt

I tried WStandardItemModel->headerDataChanged() but that did not trigger for ItemDataRole::Checked, it seems to only trigger on ItemDataRole::Display.

It's odd that you say that because in my testing it does work. I just used this code:

  model->headerDataChanged().connect([model=std::weak_ptr<Wt::WStandardItemModel>(model)](Wt::Orientation orientation,
                                                                                          const int first,
                                                                                          const int last) {
    std::cout << "Header data changed from " << first << " to " << last << '\n';
    std::cout << "Checked? " << std::boolalpha <<
       Wt::cpp17::any_cast<bool>(model.lock()->headerData(first, orientation, Wt::ItemDataRole::Checked)) << '\n';
  });

I had it set up like this.....

'''
model->headerDataChanged().connect(= {}
'''

I changed it to your model=std::weak_ptr and it now works.

I don't know why this works, but I'm sure it's c++ related and not Wt related.

Thank you and I will go research and expand my knowledge of this area of c++.

I'm not sure why that would matter. The reason I used a weak_ptr is that I would otherwise have a memory leak due to the model indirectly having a shared pointer to itself:

• The model owns the headerDataChanged() signal
• The signal owns any connected slots
• One of the slots contains a shared_ptr to the model