First, my hat's off to Sandy. She did a great job. Second, a solution for the 2nd problem: I think you need to use the -confine option.  -confine => 1 won't allow the display to go outside the scroll region; instead, using -confine => 0 will. Then

my $c = $mw->Scrolled('Canvas',
    -confine => 0
    -width => 200,
    -height => 200,
    -background =>'blue'
    -scroll => [ 0, 0, 500, 500 ]
)->pack(-expand => -2, -fill => 'both');

MainLoop;
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