This example shows the entry widget.

An entry widget is a place where the user can type one line of text.

- The init parameter allows to specify a text to place in the entry when the window is created.
- The handle parameter allows to specify a variable that can control the entry.
- The return parameter allows to specify a variable that will be binded to the text in the entry when the window is closed.
- The action parameter allows to specify a command to be executed each time the user modifies the entry.

