Tk Source Code

    /*
     * Handle pure modifier keys specially. We use -1 as a signal for
     * this.
     */

    if (eventPtr->xany.send_event == -1) {
	int modifier = eventPtr->xkey.keycode;
	int modifier = eventPtr->xkey.keycode & NSDeviceIndependentModifierFlagsMask;

	if (modifier == NSCommandKeyMask) {
	    return XK_Meta_L;
	} else if (modifier == NSShiftKeyMask) {
	    return XK_Shift_L;
	} else if (modifier == NSAlphaShiftKeyMask) {
	    return XK_Caps_Lock;