Function installMessageHook

Parameters

• handler: IMessageHandler

  The message handler of interest.

• hook: MessageHook

  The message hook to install.

  Notes

  A message hook is invoked before a message is delivered to the handler. If the hook returns false, no other hooks will be invoked and the message will not be delivered to the handler.

  The most recently installed message hook is executed first.

  If the hook is already installed, this is a no-op.