http://qs321.pair.com?node_id=280409


in reply to Tk widget derivation problems

I recall reading somewhere that the -background and -foreground options are special-cased in a few places in the Tk code and that this can cause unpredictable behavior in some cases (or something to that effect). Adding entries for the options to the call to ConfigSpecs should solve the problem: 

  $self->ConfigSpecs(
      -background   => [qw/SELF Background background/],
      -foreground   => [qw/SELF Foreground foreground/],
      'DEFAULT'     => [ 'SELF' ],
  );

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Re: Re: Tk widget derivation problems
by anjiro (Beadle) on Aug 03, 2003 at 09:37 UTC
    That does it, all right. I actually just got a similar reply on the ptk mailing list; the person said that -foreground and -background are a little funny because they're aliased to -fg and -bg.

    Thanks a lot!

    Daniel Ashbrook

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      Interesting, in Derived.pm and Widget.pm you see a similar constructs only opposite 
      $specs->{'-foreground'} = \@fg,'foreground','Foreground',BLACK];

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      Widget.pm 
       $cw->ConfigSpecs('-scrollbars' => ['METHOD','scrollbars','Scrollbars'
+,'se'],
                  '-background' => [$w,'background','Background'],
                  '-foreground' => [$w,'foreground','Foreground'],

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      I think it would be interesting to know what this is doing...
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