... the problem is how do you detect the end of playback... is some signal emitted?

.... i leave the state logic broken, for you to figure out :-)

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

my $mw     = Tk::MainWindow->new;
my $button = $mw->Button->pack(-side =>'left');
my $button1 = $mw->Button(-text => 'Go  ', 
 -state => 'normal')->pack( -side =>'left');


my $x      = $mw->Pixmap(
        -data => qq(/* XPM */
static char * x_xpm[] = {
"24 24 2 1",
"       c None",
".      c #000000",
"                        ",
"                        ",
"                        ",
"                        ",
"                        ",
"                        ",
"       ...    ...       ",
"        ..    ..        ",
"        ...  ..         ",
"         .. ...         ",
"          ....          ",
"          ...           ",
"          ...           ",
"          ....          ",
"         .. ..          ",
"        ...  ..         ",
"        ..   ...        ",
"       ..     ..        ",
"      ...     ...       ",
"                        ",
"                        ",
"                        ",
"                        ",
"                        "};
));

my $o      = $mw->Pixmap(
        -data => qq(/* XPM */
static char * o_xpm[] = {
"24 24 2 1",
"       c None",
".      c #000000",
"                        ",
"                        ",
"                        ",
"                        ",
"                        ",
"                        ",
"         ......         ",
"        ........        ",
"       ...    ...       ",
"       ..      ..       ",
"      ..        ..      ",
"      ..        ..      ",
"      ..        ..      ",
"      ..        ..      ",
"      ..        ..      ",
"       ..      ..       ",
"       ...    ...       ",
"        ........        ",
"         ......         ",
"                        ",
"                        ",
"                        ",
"                        ",
"                        "};
));

my @toggle = ($x, $o);
my @toggle1 = ('Go  ','Whoa');

$button->configure(
        -image => $x,
        -command => sub {
                @toggle = @toggle[1, 0];
                @toggle1 = @toggle1[1, 0];
                $button->configure(-image => $toggle[0]);
                
                if ( $toggle1[0] eq 'Go  '){ 
                $button1->configure( -text => $toggle1[0],
                                     -state => 'normal',
                                     );
                 }else{
                $button1->configure( -text => $toggle1[1],
                                     -state => 'disabled',
                                     );
                }     

        }
);


Tk->MainLoop;
[download]

Yup, I found that method myself, after some digging.

How I'm detecting the end of playback is a little sneaky.  I'm spawning the CLI MP3 player application like this:

    $cmd = sprintf($opts{playercmd},
                      ($listbox->getRow($i))[0]);
    $player_pid = open($PLAYER, "|$cmd");
[download]

This gets me a blocking open on the player, so that I don't ever get two tracks playing at once, and a child PID back.  But, the child player doesn't terminate on exit.  So then I poll /proc/pid/status every 50ms in my non-Tk event loop, and wait for the status to change to 'zombie', at which point I know playback has finished.  Then I can close the player handle, do any necessary processing, and advance to the next track.  The 50ms response time is too short for the listener to notice, but slow enough in system terms that the task load from the polling is down in the noise.

and wait for the status to change to 'zombie'

ha ha ha.... that has got to be the funkiest hack i've ever seen....... didn't they teach you at wizard school to never, NEVER allow zombies even into existence?.... still laughing

To give you a clue: once you have the filehandle to the process, you can watch for the filehandle( or its filenum' ) to be closed , and then do a kill -9 on the $parent_pid ..... see Perl/Tk front-end to mplayer for other ideas

---

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku

This doesn't really answer the question.  This illustrates a checkbutton which has different bitmaps for its selected and unselected states.  A checkbutton, however, has persistent state.  What I need to do is have a regular pushbutton which changes its button bitmap, in a persistent fashion, both in response to UI actions and to remote commands not involving the UI, and which may have more than two visual states.

I've subsequently discovered that there is, indeed, a simple way to do this; but the documentation of the method is somewhat obscurely buried in Tk::options.  That method is as simple as this:

$button->configure(-bitmap => 'MyNewBitmap');
[download]

Using this method, I now have multimode buttons that change their button image and foreground color as appropriate depending on what the application is doing, exactly as I wanted.