Re: better control of Tk::Button

Hi,

You can disable the Button from inside the -command callback like so:

use strict;
use warnings;
use Tk;
require Tk::BrowseEntry;

#########################
#Hitting the button casuses many instances of listBrowse widget
########################

my $listButton;
my $main= MainWindow->new();
$listButton=$main->Button(  
        -text=>   'list',
        -height=>  2,
        -width=>   10,
        -relief=>  'ridge',
        -command=> sub{listBrowse();
                       $listButton->configure(-state => 'disabled');
                       },
        )->pack();

my $choice="number"; #the default list item.
sub listBrowse{
       my $listTag=$main->BrowseEntry(
                -variable=>\$choice,
                -browsecmd=>\&Verify
                )->pack();
        $listTag->insert("end","Number");
        $listTag->insert("end","Bullet");

        }
MainLoop;
[download]

Cheers, Christoph

Comment on Re: better control of Tk::Button Select or Download Code

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Re^2: better control of Tk::Button by SuicideJunkie (Vicar) on Oct 07, 2009 at 14:13 UTC
One problem with doing the disable alone is that it does not completely prevent multiple click events from occurring. If the app is busy, a second click could be done before the first click is handled and the button is disabled. Scripts such as Autohotkey for windows can also send the events despite the disabled-ness of the button. The better way to go about this, is to check whether there is already a listBrowse widget in existence. If one already exists, you can destroy the old one and replace it, or skip the creation of a new one, whichever makes the most sense. As for storing the flag as in the OP's original plan, all you should need is a variable that is scoped to cover the right region: `... { # Extra scope to keep $menuPopped contained to just this region. my $menuPopped = 0; sub thatReadsFlag { ... if ($menuPopped) {} ... } sub thatWritesFlag { ... $menuPopped = shift; ... } } ...` [download] - SJ How to make perldoc.perl.org resizable too!	[reply] [d/l]
Re^3: better control of Tk::Button by lamprecht (Friar) on Oct 07, 2009 at 18:17 UTC
'One problem with doing the disable alone is that it does not completely prevent multiple click events from occurring. If the app is busy, a second click could be done before the first click is handled and the button is disabled.' I could have sworn, that this second click would be discarded by the Button instance, unless you insert an `update()` call in between the `listBrowse()` call and the setting of disabled state. And I'm still sure that this is true for Button-Click events. However there is a bug in Tk::Buttons implementation of the `'<Return>'` event handler `Invoke()` (note the capitalization) which can lead to a race condition where `-state` is not handled correctly in case of multiple `'<Return'>` events in the queue. So +++ to your reply. Cheers Christoph update: https://rt.cpan.org/Ticket/Display.html?id=50330	[reply] [d/l] [select]