class ABC: public TopWindow
{
    bool blink;
    void ChangeBilnk1();
    void ChangeBilnk2();
   ...
}

// ABC.blink initalized with "true" - !!! I was wrong !!!

ABC::ChangeBlink1()
{
 blink = !blink;  // 'blink' NOT change value;
}

ABC::ChangeBlink2()
{
 blink = (blink ? false : true ); // 'blink' change value
}