procedure
                        :choice         name

Creates a choice widget within the current panel frame for the TCL
interpreter. A choice widget is a frame window containing a number of
checkbutton windows and (optionally) a label window.
name is used to generate the path name of the windows to be created. It
should have the format of a widget name  (e.g.  :choice   CH) and should be
unique within this interpreter. The name will be lower-cased (using the string
tolower command) in order to generate the path name used to create the
windows.
When a choice is selected by releasing mouse button 1 while the mouse
focus is on the choice then the TCL command
click  FRAME “ ” CHOICE value
will be executed where FRAME and CHOICE are widget names and value is
determined by which choice or choices are currently selected (see :exclusive).
The path names generated have the root framename.panelname.choice-
name and the items label and button*.
The :choice procedure may also be used directly within a frame window (i.e. before any panel
window has been created).


The :choice procedure may have a number of arguments however none of
these is mandatory.

        arguments
                        :x                      number
        number is the x-co-ordinate within the current panel of the choice
widget in pixels
        e.g.    :x 400

                        :y                      number
        number is the y-co-ordinate within the current panel of the choice
widget in pixels
        e.g.    :y 200
The :x and :y parameters may be omitted in which case the packer geometry manager will be
used and the position of the window will be determined by the contents of the master (panel)
window. If however the :x and :y parameters are supplied then the placer geometry manager
will be used to position the window within the master (panel) window.
Warning:        Note that it is not possible to mix use of the packer and placer geometry
managers within the same window. Thus all windows within a panel must request or imply that
the same geometry manager is used.

                        :w                      value
        value is the width of the checkbutton windows in characters.
        e.g.    :w 10


                        :value                  value
        value determines the initially selected checkbutton or checkbuttons
(see :exclusive).
The default value is 0 (no items selected).

                        :valuex         value
        value is the position of the right hand edge of the label window with
relation to the left hand edge of the choice widget. It is thus the space
available to write the label string but also allows alignment of the checkbutton
windows of several choice widgets. The value may be expressed in units of
pixels or characters.
        e.g.    :valuex 100    (pixels);        :valuex 15c    (characters)
The default value is 0. If :valuex is specified then a label window will be created even if :label
is not specified (in which case the label will be a single space character).

                        :label                  string
        string is a text string to be written into the label component of the
choice widget.
By default no label window is created. A non null :label string ( a single space is adequate)
causes the label window to be created (see also :valuex)..

                        :strings                list
        list is a TCL list of strings. For each item in the list a checkbutton
window is created and the item string is written onto the checkbutton.
The default is a null list.

                        :layout         V|H
        defines the layout (Vertical or Horizontal) of the components of the
choice widget.
The default layout is H.

                        :exclusive              T|F
        If True then only one checkbutton at a time may be selected and :value
defines the index of the selected checkbutton within the list of available
checkbuttons. If False then any number of checkbuttons may be selected and
value is a bitmap which defines the selected checkbuttons within the list of
available checkbuttons. The low order bit of the bitmap corresponds to
checkbutton index = 0.
The default is T.

See also common procedure arguments defined later in this document.