$canvas->update; 

$mainWindow->update;

sub showPosData
{
  control::geti2caddress($i2c);
  my $robot = shift;
  my $target = shift;
  my $dist;
  $posshow->delete('all'); #Canvas das die Positionen anzeigen soll(te)
  {
    foreach (sort keys %$oo)
    {
      if ($oo->{$_}{pos}{x} > 0 and $oo->{$_}{pos}{y} > 0)
      {
        my $color = 'blue';
        $color = 'red' if ($oo->{$_}{mode} eq 'active');
        pos::createText($posshow, $oo->{$_}, $_, $color); #erstellt die Texte fürs canvas
      }
      else
      {
        control::stopmotor();
      }
    }
    my $targetangle = pos::calcDirection($oo, $currentactive, $currentpassive);
    my ($x, $y) = pos::createAngle($targetangle);

    $posshow->createLine($oo->{$robot}{pos}{x}, $oo->{$robot}{pos}{y}, $oo->{$robot}{pos}{x} + $x, $oo->{$robot}{pos}{y} + $y, -fill => 'red', -arrow => 'last');

[ ... ]

    $posshow->update; #Canvas aktualisieren... geht aber nicht :((((
  }
}