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.\"
.IX Title "Menu::Item 3"
.TH Menu::Item 3 2023-07-25 "perl v5.38.0" "User Contributed Perl Documentation"
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.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
Tk::Menu::Item \- Base class for Menu items
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&   require Tk::Menu::Item;
\&
\&   my $but = $menu\->Button(...);
\&   $but\->configure(...);
\&   my $what = $but\->cget();
\&
\&   package Whatever;
\&   require Tk::Menu::Item;
\&   @ISA = qw(Tk::Menu::Item);
\&
\&   sub PreInit
\&   {
\&    my ($class,$menu,$info) = @_;
\&    $info\->{\*(Aq\-xxxxx\*(Aq} = ...
\&    my $y = delete $info\->{\*(Aq\-yyyy\*(Aq};
\&   }
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Tk::Menu::Item is the base class from which Tk::Menu::Button,
Tk::Menu::Cascade, Tk::Menu::Radiobutton and Tk::Menu::Checkbutton are derived.
There is also a Tk::Menu::Separator.
.PP
Constructors are declared so that \f(CW$menu\fR\->Button(...) etc. do what you would
expect.
.PP
The \f(CW\*(C`\-label\*(C'\fR option is pre-processed allowing ~ to be prefixed to the character
to derive a \f(CW\*(C`\-underline\*(C'\fR value. Thus
.PP
.Vb 1
\&    $menu\->Button(\-label => \*(AqGoto ~Home\*(Aq,...)
\&
\&    is equivalent to
\&
\&    $menu\->Button(\-label => \*(AqGoto Home\*(Aq, \-underline => 6, ...)
.Ve
.PP
The \f(CW\*(C`Cascade\*(C'\fR menu item creates a sub-menu and accepts
these options:
.IP \fB\-menuitems\fR 4
.IX Item "-menuitems"
A list of items for the sub-menu.
Within this list (which is also accepted by Menu and Menubutton) the first
two elements of each item should be the "constructor" name and the label:
.Sp
.Vb 4
\&    \-menuitems => [
\&                   [Button      => \*(Aq~Quit\*(Aq, \-command => [destroy => $mw]],
\&                   [Checkbutton => \*(Aq~Oil\*(Aq,  \-variable => \e$oil],
\&                  ]
.Ve
.IP \fB\-postcommand\fR 4
.IX Item "-postcommand"
A callback to be invoked before posting the menu.
.IP \fB\-tearoff\fR 4
.IX Item "-tearoff"
Specifies whether sub-menu can be torn-off or not.
.IP \fB\-menuvar\fR 4
.IX Item "-menuvar"
Scalar reference that will be set to the newly-created sub-menu.
.PP
The returned object is currently a blessed reference to an array of two items:
the containing Menu and the 'label'.
Methods \f(CW\*(C`configure\*(C'\fR and \f(CW\*(C`cget\*(C'\fR are mapped onto underlying \f(CW\*(C`entryconfigure\*(C'\fR
and \f(CW\*(C`entrycget\*(C'\fR.
.PP
The main purpose of the OO interface is to allow derived item classes to
be defined which pre-set the options used to create a more basic item.
.SH BUGS
.IX Header "BUGS"
This OO interface is very new. Using the label as the "key" is a problem
for separaror items which don't have one. The alternative would be to
use an index into the menu but that is a problem if items are deleted
(or inserted other than at the end).
.PP
There should probably be a PostInit entry point too, or a more widget like
defered 'configure'.