my @box;                 # Tracks the IDs of each rectangle
my $viewable_width=400;  # How wide is the viewable Canvas?

##</code><code>##

    $sc[$i] = $tile[$i]->Scrolled('Canvas',
            -scrollbars => 'os',
            -scrollregion => [0, 0, $initial_width, 125],
            -width => $viewable_width,
            -height => 125,
            -background => randColor()
    )->pack(qw/-fill both -side top -expand 1/);

##</code><code>##

    $box[$i] = $sc[$i]->createRectangle($x, 50, $x+20, 90,
            -fill => randColor(),
            -outline => 'black',
            -width => 2,
            -tags => 'rect',
     );

##</code><code>##

sub AlignAll{
    my ($x1, $y1, $x2, $y2);
    foreach my $i (0 .. 3) {
        my $sc = $sc[$i];                           # Get Canvas object
        my $box = $box[$i];                         # Get box id (rectangle)
        my ($x1, $y1, $x2, $y2) = $sc->bbox($box);  # Get box coordinates
        my $mid = ($x1 + $x2) / 2;                  # Get midpoint, minus
        $mid -= $viewable_width / 2;                #   1/2 of visible window
        my $newx = $mid / $initial_width;           # Get delta x-distance
        $sc->xviewMoveto($newx);                    # Move Canvas object
    }
}

##</code><code>##

$frame->Button(
   -text => " Zoom Out ",
   -width => 10,
   -command => sub {
        $scale*=0.8;
        $initial_width *= $scale;
        foreach  $i (0 .. 3) {
            $sc[$i]->scale(qw/all 0 0 .8 1/);
            $sc[$i]->configure(-scrollregion => [0, 0, $initial_width, 125]);
        }
    }
)->pack(qw/-side left -padx 25/);
$frame->Button(
   -text => " Zoom In ",
   -width => 10,
   -command => sub {
        $scale*=1.25;
        $initial_width *= $scale;
        foreach  $i (0 .. 3) {
            $sc[$i]->scale(qw/all 0 0 1.25 1/);
            $sc[$i]->configure(-scrollregion => [0, 0, $initial_width, 125]);
        }
    }
)->pack(qw/-side left -padx 25/);