A filechooser may be used to select files from the current
working directory.
Selecting a file may be done by double clicking on an
item in the listbox or by typing a name in the entry.
To confirm the choice, either the OK button must
be pressed.
Giving a return in the entry has the same effect.
The dialog may be interrupted by pressing the cancel
button.
An action or handler may be attached to the filechooser.
It is activated when either the OK and cancel
is pressed.
The name of the button is given as an additional
argument when calling the handler.