Beci has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks,

I'd like to run another program from my script. Both programs have a Tk interface. My problem is that when child exits, the MainWindow of the main script loses focus. It is a problem for me because the main program uses a barcode reader in keyboard emulation mode. When the MainWindow loses its focus, the bindings of the keyboard to $mw don't work, of course. I don't want to tell the operators to left-click into $mw before using the barcode reader.

Is there a way to give the focus back to $mw after the child process closes? Here is my code, it doesn't give back te focus:

$mw->iconify;
$mw->withdraw;

unless(open(HND,"<vmapper.ini"))
 {
  &fileRdWrError('vmapper.ini','read','p1_appendMsgToLog');
  exit 0;
 }
my $line = <HND>; chomp $line;
close HND;
system($line.'vmapper.exe');
#other program exited, continue from here
$mw->raise;
$mw->deiconify;
$mw->update;
$mw->focus; #should give the focus back here

[download]
Thanks,

Beci

Replies are listed 'Best First'.
Re: Tk focus
by Anonymous Monk on Jan 08, 2012 at 20:14 UTC

    I'd like to run another program from my script. Both programs have a Tk interface.

    There is your problem. What should have been a Tk::Dialog you've turned into another app.

    Anyway, it works for me, and focusForce overrides the blinking taskbar behaviour on win32 (which I'm fond of, since I don't like apps to steal the focus from me) 

    #!/usr/bin/perl --
use strict; use warnings;
use Tk;

my $mw = tkinit();

$mw->Button(
    -text =>  'go' ,
    -command => sub {
        $mw->Busy;
        $mw->iconify;
        $mw->withdraw;
        
        system $^X, '-MTk', '-e', 'tkinit;MainLoop' ;
        
        $mw->raise;
        $mw->deiconify;
        $mw->update;
        $mw->focus;
        $mw->Unbusy;
        $mw->focus;
        $mw->focusForce; # win32
        
        return;
    },
)->pack;

MainLoop();

    [download]
[reply]
[d/l]

      Hi,

      This helped, the main app gets the focus back when the other exits.

      Thanks a lot for you and Khen1950fx also!

      Beci
[reply]
Re: Tk focus
by Khen1950fx (Canon) on Jan 08, 2012 at 17:44 UTC
    The snippet that you've provided isn't workable. That said, you want to see the man page for Tk::focus. It's a built-in for Tk, so just enter 
    man focus

    [download]
    It should answer your question.
[reply]
[d/l]

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