Hi,
the following code will draw a line from top left to bottom right in win32gui and TK, the condition is that i must draw it once only ie executing the plotting code once only.
win32gui : 
use strict;
use warnings;

use Win32::GUI();
our $NumberOfLinesDrawn = 0;
my $Win = new Win32::GUI::Window(
    -left   => 0,
    -top    => 0,
    -width  => 500,
    -height => 400,
    -name   => "Window",
    -text   => "drawing a line",
    ##-onPaint => \&Draw,
   
);

$Win->Show();
Draw();
Win32::GUI::Dialog();

sub Window_Terminate {
    return -1;
}

sub Draw {
        my $DC = $Win->GetDC;
        my $x  = 0;
        my $y  = 0;
        for(1..300) {$y +=1; $x +=1;
            $DC->SetPixel($x,$y);
                }
    ##$DC->Validate();
    $NumberOfLinesDrawn +=1;
    print "$NumberOfLinesDrawn\n";
    }

[download]
so in win32gui how to keep the plot from been erased when covered by other windows !!. the usual plan for this is to redraw the same line code again and again if you uncomment the lines: 
-onPaint => \&Draw
##and
$DC->Validate();

[download]
but i think this is not the same way other modules or languages deals with updating the window ie by updating the pixels of the screen, in comparison the same TK code is concise and working well: 
use warnings;
use strict;        
use Tk;
my $mw = MainWindow->new;  
my $x = 0; my $y = 0;
my $counter=0;
our $NumberOfLinesDrawn = 0;

my $c = $mw->Canvas(-width => 500, -height => 500);
$c ->pack;

for(1..300) {$y +=1; $x +=1;
 
  $c -> createText( $x, $y, -fill => 'red', -text => '.');
        
        
        }
        $mw->update;
        $NumberOfLinesDrawn +=1;
        print "$NumberOfLinesDrawn\n";
        MainLoop;

[download]

In reply to updating the window in Win32 GUI by Anonymous Monk

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