[moal]

You can use dynamic_cast instead of reinterpret_cast. If the pointer isn't correct it would return null. A better solution is to subclass the widget, store a function pointer for the callback which takes the same class instead of an Fl_Widget, and call that in the callback: https://github.com/MoAlyousef/FLMH This uses a std::function for the captures but you can use a function pointer as well.