3.10  choice%

Implements: list-control<%>

A choice item allows the user to select one string item from a pop-up list of items. Unlike a list box, only the currently selection is visible until the user pops-up the menu of choices.

Whenever the selection of a choice item is changed by the user, the choice item's callback procedure is invoked. A callback procedure is provided as an initialization argument when each choice item is created.

See also list-box%.

• (new choice% (label _) (choices _) (parent _) [(callback _)] [(style _)] [(selection _)] [(font _)] [(enabled _)] [(vert-margin _)] [(horiz-margin _)] [(min-width _)] [(min-height _)] [(stretchable-width _)] [(stretchable-height _)]) -> choice% object
     label : string (up to 200 characters) or #f
   choices : list of strings (up to 200 characters each)
     parent : frame%, dialog%, panel%, or pane% object
     callback = (lambda (c e) (void)) : procedure of two arguments: a choice% object and a control-event% object
     style = null : list of symbols in '(vertical-label horizontal-label deleted)
   selection = 0 : exact non-negative integer
     font = normal-control-font : font% object
     enabled = #t : boolean
     vert-margin = 2 : exact integer in [0, 1000]
     horiz-margin = 2 : exact integer in [0, 1000]
     min-width = graphical minimum width : exact integer in [0, 10000]
     min-height = graphical minimum height : exact integer in [0, 10000]
     stretchable-width = #f : boolean
     stretchable-height = #f : boolean

  Creates a choice item. If label is a string, it is used as the label for the choice item.

  If an ampersand (``&'') occurs in label, it is specially parsed; under Windows and X, the character following an ampersand is underlined in the displayed control to indicate a keyboard mnemonic. (Under Mac OS X, mnemonic underlines are not shown.) The underlined mnemonic character must be a letter or a digit. The user can move the keyboard focus to the choice item by typing the mnemonic when the control's top-level-window contains the keyboard focus. The user must also hold down the Meta or Alt key if the keyboard focus is currently in a control that handles normal alphanumeric input. The ampersand itself is removed from label before it is displayed for the control; a double-ampersand in label is converted to a single ampersand (with no mnemonic underlining). Under Mac OS X, a parenthesized mnemonic character is removed (along with any surrounding space) before the label is displayed, since a parenthesized mnemonic is often used for non-Roman languages. Finally, any text after a tab character is removed on all platforms. Mnemonic keyboard events are handled by on-traverse-char (but not under Mac OS X).

  The choices list specifies the initial list of user-selectable items for the control. The initial set of choices determines the control's minimum graphical width (see Geometry Management for more information).

  The callback procedure is called (with the event type 'choice) when the user selects a choice item (or re-selects the currently selected item).

  If style includes 'vertical-label, then the choice item is created with a label above the control; if style does not include 'vertical-label (and optionally includes 'horizontal-label), then the label is created to the left of the choice item. If style includes 'deleted, then the choice item is created as hidden, and it does not affect its parent's geometry; the choice item can be made active later by calling parent's add-child method.

  By default, the first choice (if any) is initially selected. If selection is positive, it is passed to set-selection to set the initial choice selection. Although selection normally must be less than the length of choices, it can be 0 when choices is empty.

  The font argument determines the font for the control. For information about the enabled argument, see window<%>. For information about the horiz-margin and vert-margin arguments, see subarea<%>. For information about the min-width, min-height, stretchable-width, and stretchable-height arguments, see area<%>.

  
  

All Methods
    accept-drop-files from window<%>
    append from list-control<%>
    clear from list-control<%>
    client->screen from window<%>
    command from control<%>
    enable from window<%>
    find-string from list-control<%>
    focus from window<%>
    get-client-size from window<%>
    get-cursor from window<%>
    get-font from control<%>
    get-graphical-min-size from area<%>
    get-handle from window<%>
    get-height from window<%>
    get-label from window<%>
    get-number from list-control<%>
    get-parent from area<%>
    get-plain-label from window<%>
    get-selection from list-control<%>
    get-size from window<%>
    get-string from list-control<%>
    get-string-selection from list-control<%>
    get-top-level-window from area<%>
    get-width from window<%>
    get-x from window<%>
    get-y from window<%>
    has-focus? from window<%>
    horiz-margin from subarea<%>
    is-enabled? from window<%>
    is-shown? from window<%>
    min-height from area<%>
    min-width from area<%>
    on-drop-file from window<%>
    on-focus from window<%>
    on-move from window<%>
    on-size from window<%>
    on-subwindow-char from window<%>
    on-subwindow-event from window<%>
    on-superwindow-enable from window<%>
    on-superwindow-show from window<%>
    popup-menu from window<%>
    refresh from window<%>
    screen->client from window<%>
    set-cursor from window<%>
    set-label from window<%>
    set-selection from list-control<%>
    set-string-selection from list-control<%>
    show from window<%>
    stretchable-height from area<%>
    stretchable-width from area<%>
    vert-margin from subarea<%>