I'm drawing stuff in a window, then minimizing the window to the bottom part of the screen using the Windows underscore symbol.  When my mouse hovers over the minimized icon, the content is still there.  When I click on the icon to reopen the window, the content is gone.  

Simple example included below, where the top half of the window is painted green, the bottom part red.

I assume it's some magic to do with dc, onEvent, save, restore etc., but I can't figure it out.  

In case my setup matters:

Windows 7 SP1
CYGWIN_NT-6.1-WOW64 1.7.17(0.262/5/3) 2012-10-19 14:39
perl 5.14
Win32::GUI v1.06 (GUI.pm 1.69)


use strict;
use warnings;
use Win32::GUI();

my $WIDTH  = 400;
my $HEIGHT = 600;

my $win = Win32::GUI::Window->new(
    -name => 'win', -width => $WIDTH, -height => $HEIGHT );


sub make_example
  my $dc    = $win->GetDC;
  my $brush = new Win32::GUI::Brush( [32, 128, 32] );
  my $old_brush = $dc->SelectObject($brush);
  $dc->Rectangle(0, 0, $WIDTH, $HEIGHT/2);
  $brush = new Win32::GUI::Brush( [178, 63, 63] );
  $dc->Rectangle(0, $HEIGHT/2, $WIDTH, $HEIGHT);
  $dc->SelectObject($old_brush) if defined ($old_brush);

sub win_Terminate { -1; }