FLTK自定义组件中Tooltip无法正常显示的问题求助

我正在使用Fl_Tabs及自定义组件开发项目工具，这些自定义组件依赖其他自定义类。目前遇到的问题是：鼠标悬停在自定义组件上时，Tooltip无法正常显示。我尝试了多种排查方式但未解决，认为遗漏了关键细节：

• 根据FLTK官方文档说明：

  The internal copy will automatically be freed whenever you assign a new tooltip or when the widget is destroyed.
  我曾误以为组件处于Fl_Group内时Tooltip会被释放，但实际并非如此，如下方代码所示。

• 由于我重写了handle函数，虽仅处理FL_PUSH事件，其余事件均交由FLTK原生处理，但仍怀疑这会影响Tooltip的行为。

以下是可复现该问题的代码片段，包含了场景中的所有元素：

#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Tabs.H>
#include <FL/Fl_Group.H>
#include <FL/Fl_Button.H>
#include <FL/Fl_Box.H>

#include <iostream>

class Action{
    public: 
        Action(std::string name, int cInit){
            _name = name;
            _counter = cInit;
        };

        void increment(){
            _counter++;
        };

        std::string message(){
            increment();
            return _name + " Counter: " + std::to_string(_counter);
        };

    private:
     std::string _name;
     int _counter;
};

class MyButton: public Fl_Box{
    public:
        MyButton(int X, int Y, int W, int H, Action* A, Fl_Box* mb, const char* L=0):Fl_Box(X,Y,W,H,L){
            box(FL_UP_BOX);
            _mb = mb;
            _A = A;
        }

        int handle(int event){
             switch(event) {
                case FL_PUSH:
                    sendMessage();
                    return 0;
                default:
                    return Fl_Widget::handle(event);
            }
        };

        void sendMessage(){
            _mb->copy_label(_A->message().c_str());
        };

    private:
        Fl_Box* _mb;
        Action* _A;
};


int main(int argc, char *argv[]) {
    Fl_Window *win = new Fl_Window(500,300,"Tabs Example");
    {
        Action* A = new Action("Trees",42);
        Fl_Box* B = new Fl_Box(10,210,150,50);
        B -> box(FL_UP_BOX);
        Fl_Tabs *tabs = new Fl_Tabs(10,10,500-20,200-20);
        {
            // Aaa tab
            Fl_Group *aaa = new Fl_Group(10,35,500-20,200-45,"Aaa");
            {
                MyButton *b1 = new MyButton(50, 60,90,25,A,B,"Button A1"); b1->color(88+1);
                Fl_Box *b2 = new Fl_Box(50, 90,90,25,"Button A2"); b2->box(FL_UP_BOX); b2->color(88+2);
                Fl_Button *b3 = new Fl_Button(50,120,90,25,"Button A3"); b3->color(88+3);

                b1 -> copy_tooltip("b1: is it there?");
                b2 -> copy_tooltip("b2: is it there?");
                b3 -> copy_tooltip("b3: is it there?");
            }
            aaa->end();

            // Bbb tab
            Fl_Group *bbb = new Fl_Group(10,35,500-10,200-35,"Bbb");
            {
                Fl_Button *b1 = new Fl_Button( 50,60,90,25,"Button B1"); b1->color(88+1);
                Fl_Button *b2 = new Fl_Button(150,60,90,25,"Button B2"); b2->color(88+3);
                Fl_Button *b3 = new Fl_Button(250,60,90,25,"Button B3"); b3->color(88+5);
                Fl_Button *b4 = new Fl_Button( 50,90,90,25,"Button B4"); b4->color(88+2);
                Fl_Button *b5 = new Fl_Button(150,90,90,25,"Button B5"); b5->color(88+4);
                Fl_Button *b6 = new Fl_Button(250,90,90,25,"Button B6"); b6->color(88+6);
            }
            bbb->end();
        }
        tabs->end();

       
    }
    win->end();
    win->show();
    return(Fl::run());
} 

开发环境：FLTK 1.3.5、clang 14.0.0，设备为搭载Monterey系统（12.6.1）的MacBookPro。

内容的提问来源于stack exchange，提问作者Eddymage