ref: 948870cffe2572efb68ef0b3873b36238fb53263
dir: /man/2/popup/
.TH POPUP 2
.SH NAME
Popup: mkbutton, changebutton, event, add \- popup list box pseudo-widget
.SH SYNOPSIS
.EX
include "popup.m";
popup := load Popup Popup->PATH;
init: fn();
mkbutton: fn(win: ref Tk->Toplevel, name: string,
items: array of string, n: int): chan of string;
changebutton: fn(win: ref Tk->Toplevel, name: string,
items: array of string, n: int);
event: fn(win: ref Tk->Toplevel, e: string,
items: array of string): int;
add: fn(items: array of string, s: string):
(array of string, int);
.EE
.SH DESCRIPTION
.B Popup
implements popup list boxes as Tk pseudo-widgets.
This module has since been superseded by
.IR choicebutton (2)
in Tk itself, but remains for the moment for compatibility.
.PP
.B Init
must be called once to initialise the module.
.PP
.B Mkbutton
creates a new button
.IR name ,
in Tk toplevel
.IR win .
It returns a channel on which it delivers events (see
.BR event ,
below).
Once created,
.I name
can be packed like any other Tk widget.
When the button is pressed with button 1,
a menu pops up offering a choice from the given
.IR items .
The value
.I n
is the index in
.I items
of the button's initial value.
The current choice is always displayed in the button.
If
.I items
is nil or an empty array, the string
.RB ` ----- '
is displayed instead.
.PP
Having created a popup button, the application must receive values on
the channel returned by
.B mkbutton
and pass each value it receives to
.BR event
(as parameter
.IR e ).
(Typically the application will receive on the channel in an
.B alt
statement that watches other channels too.)
.B Event
returns the result of a selection, or -1 if no selection was made.
In either case, the text of the button
.I name
will reflect the currently active selection
(the application can fetch it using
.RB ` cget\ -text ').
The
.I items
parameter must match that given to
.B mkbutton
(or most recently given to
.BR changebutton ).
.PP
.B Changebutton
changes the list of
.I items
in an existing popup button
.IR name ,
and sets its initial selection to the item with index
.IR n .
.PP
.B Add
adds string
.I s
to the array
.IR items ,
if it is not already there,
and in either case returns the resulting new array and
the index of
.I s
therein.
It is useful for calculating a list of items dynamically.
.SH SOURCE
.B /appl/lib/popup.b
.SH SEE ALSO
.IR tabs (2),
.IR tk (2)