code: func (v *Assistant) SetPageTitle(page IWidget, title string) {
  	cstr := C.CString(title)
  	defer C.free(unsafe.Pointer(cstr))
  	C.gtk_assistant_set_page_title(v.native(), page.toWidget(),
  		(*C.gchar)(cstr))
  }
docs: // SetPageTitle is a wrapper around gtk_assistant_set_page_title().