Fl_End
#include <FL/Fl_Group.H>
class MyClass { Fl_Group group; Fl_Button button_in_group; Fl_End end; Fl_Button button_outside_group; MyClass(); }; MyClass::MyClass() : group(10,10,100,100), button_in_group(20,20,60,30), end(), button_outside_group(10,120,60,30) {}