code: func (v *ToolButton) SetIconName(iconName string) {
  	cstr := C.CString(iconName)
  	defer C.free(unsafe.Pointer(cstr))
  	C.gtk_tool_button_set_icon_name(v.native(), (*C.gchar)(cstr))
  }
docs: // SetIconName is a wrapper around gtk_tool_button_set_icon_name().