private:
bool blMyBool;

void MyClass::SetMyBool(bool aBool)
{
    blMyBool=true;
    wxPaintEvent pe;
    OnPaint(pe);//so it works (blMyBool is true)
    Refresh();//so it doesn't work
};

void MyClass::OnPaint(wxPaintEvent& event)
{
  if(MyBool)
         wxMessageBox("MyBool = true");
};

void MyClass::OnPaint(wxPaintEvent& event)
{
  if(blMyBool)
         wxMessageBox("blMyBool = true");
};