## 27.11 Listeners

The class `Tk.listener` is not a tcl object. Is main use is to serve as listener for events, see also Section 27.2.1. It provides the following methods. For an example see Section 5.6 of ``Window Programming in Mozart''.

`tkInit`

  > > `tkInit()`

  Creates a new listener, which consists of a message stream and a thread that serves each message on the stream by applying `self` to it.

`tkServe`

  > > `tkServe(``+MessageR``)`

  Adds the message `MessageR` to the current tail of the message stream.

`tkClose`

  > > `tkClose()`

  Decouples the message stream from the serving thread. That is, after all messages that are currently on the stream have been served, the serving thread terminates.