tiedlistbox(3)

NAME

Tk::TiedListbox - gang together Listboxes

SYNOPSIS

use Tk::TiedListbox
$l1 = $widget->Listbox(-exportselection => 0,...);
$l2 = $widget->Listbox(-exportselection => 0,...);
$l3 = $widget->Listbox(-exportselection => 0,...);
$l1->tie([$l2,$l3]);

DESCRIPTION

TiedListbox causes two or more Listboxes to be operated in
tandem. One application is emulating multi-column list
boxes. The scrolling, selection, or both mechanisms may be
tied together. The methods tie and untie are provided, along with overridden versions of some of the Listbox
methods to provide tandem operation.

Scrollbars are fully supported. You can use either explic
itly created Scrollbars, the ScrlListbox widget, or the Scrolled super-widget. Tricks to "attach" multiple tied
listboxes to a single scrollbar are unnecessary and will
lead to multiple calls of the listbox methods (a bad
thing).

The configuration options, geometry, and items of the
Listboxes are not altered by tying them. The programmer
will have to make sure that the setup of the Listboxes
make sense together. Here are some (unenforced) guide
lines:

For listboxes with tied selection:

· set -exportselection to 0 for all but possibly one

Listbox

· use identical -selectmode for all Listboxes

· if items are added/deleted, they should be done all at

once and at the same index, or the selection should be
cleared

· Listboxes should have the same number of items

For listboxes with tied scrolling:

· use the same window height and font for all Listboxes

· Listboxes should have the same number of items

METHODS

$listbox->tie?(?option?, [listbox,...])?

Ties together $listbox and the list of Listboxes with the given option. Returns $listbox.

If no arguments are given, returns a list containing
two items: the tie option ("scroll", "selection", or
"all") and the list of Listboxes to which $listbox is tied.

option can be one of "scroll", "selection", or "all". If omitted, "all" is assumed. "scroll" makes the tied
Listboxes scroll together, "selection" makes selec
tions occur simultaneously in all tied Listboxes, and
"all" effects both actions.

All the Listboxes are untied (if previously tied)
before being tied to each other; hence a Listbox can
only be in one "tie group" at a time. "Tiedness" is
commutative.

The tie method can be called with either Listbox or
TiedListbox objects. All Listbox objects specified are
reblessed to TiedListbox objects.

Code such as below can be used to tie ScrlListboxes:

$slb1=ScrlListbox(...); # or Scrolled('List

box',...
$slb2=ScrlListbox(...); # or Scrolled('List

box',...
$slb1->tie([$slb2->Subwidget('scrolled')]);

$listbox->uunnttiiee(())

This function unties the Listbox from its "tie group".
The other items in the "tie group" (if more than one)
remain tied to each other.

Returns a list containing two items: the old tie
option ("scroll", "selection", or "all") and the list
of Listboxes to which $listbox was tied.

OVERRIDDEN METHODS

You probably don't care about these. They are just details
to tie together the behaviors of the listboxes.

All overriden methods take identical arguments as the cor
responding Listbox methods (see Tk::Listbox for a full
description). All overridden methods that take an index
interpret that index in the context of the listbox object
provided.

$listbox->activate(...)
$listbox->selection(...)

To allow tied selection, these functions are overrid
den for listboxes tied together with the "selection"
or "all" option. When an item is selected or activated
in one listbox, the items with the same index (if pre
sent) are selected or activated in all tied listboxes.

The selection('includes',...) submethod returns only information about the given $listbox.

$listbox->scan(...)
$listbox->see(...)
$listbox->yview(...)

To allow tied scrolling, these functions are overrid
den for listboxes tied together with the "scroll" or
"all" option. When one listbox is scrolled, all the
other tied listboxes are scrolled by the same number
of items (if possible). An attempt is made to keep
items of the same index at the top of each tied list
box, while not interfering with the normal scrolling
operations.

The yview method with no arguments returns only infor
mation about the given $listbox.

Horizontal scrolling (via xview) is not tied.

BUGS

Reblessing the widgets to TiedListbox might be too weird.
It will disable any additional features for widgets in a
class derived from Listbox (none yet that I know of).

The bindtags for reblessed widgets aren't updated. This is
probably wouldn't be a good thing to do automatically any
way.

AUTHOR

Andrew Allen <ada@fc.hp.com>

This code may be distributed under the same conditions as
Perl.

perl v5.8.0 1998-09-21 TiedListbox(3)