code: func (v *StatusIcon) SetTooltipMarkup(markup string) {
  	cstr := C.CString(markup)
  	defer C.free(unsafe.Pointer(cstr))
  	C.gtk_status_icon_set_tooltip_markup(v.native(), (*C.gchar)(cstr))
  }
docs: // SetTooltipMarkup is a wrapper around gtk_status_icon_set_tooltip_markup()