c++ - Incompatible cv qualifiers in parent class method -

i'm tinkering c++ , gtkmm, trying create custom class calls upon .glade file build gtk rather basic interface. class derived gtk::window, when call get_widget method on class itself, error:

types ‘const t_widget*’ , ‘myclass* const’ have incompatible cv-qualifiers 

class definition:

class myclass: public gtk::window{      public:     myclass();       protected:     //...     glib::refptr<gtk::builder> builder;     //...  } 

however trying upload data glade file class (on class constructor):

//... builder = gtk::builder::create_from_file("../glade/myclass.glade"); builder->get_widget("window1",this); //... 

myclass* const not same const myclass*. in first 1 pointer constant, , in second 1 object is. declare : const myclass*

but problem seems unrelated (my bad), gtk has special function derived class : gtk::builder::get_widget_derived, use instead.