prima_test.pl

use strict;
use warnings;

package prima_test;

use Prima qw (Application ComboBox);

my $mw = Prima::MainWindow->create(

    # here there are some options, mainly that more common:
    size      => [ 400, 400 ],
    menuItems => [
        [
            "~File" => [
                [],    # division line
                [ "E~xit" => "Exit" ]
            ]
        ]
    ],

    # events
    onPaint => sub {
        my ( $self, $canvas ) = @_;
        $canvas->clear;
        $canvas->color( cl::Red );
        $canvas->line( 0, 0, 800, 800 );
    }
);

$mw->insert(
    'ComboBox',
    name => 'ComboBox',
    size => [ 100, 100 ],

    # other options as needed
);

Prima->run;