It works fine for me on GNU/Linux:

package Frame;

use strict;
use warnings;

use Wx qw[:everything];
use base qw(Wx::Frame);

sub new {
    my $self = shift;

    $self = $self->SUPER::new(
        undef,
        -1,
        'Test app',
        [-1, -1],
        [-1, -1],
        wxDEFAULT_FRAME_STYLE,
    );

    #- Grid Sizer
    my $sizer = Wx::GridSizer->new(2, 1);

    my $text = Wx::TextCtrl->new(
        $self, -1, q{Hello},
        [ -1, -1 ],
        [ -1, 40 ],
        wxTE_MULTILINE,
    );
    my $button = Wx::Button->new( $self, -1, '&Color',[ 70, 30 ] );

    my $hbox = Wx::BoxSizer->new(wxHORIZONTAL);

    Wx::Event::EVT_BUTTON(
        $self, $button,
        sub {
            $text->SetForegroundColour( Wx::Colour->new(255,0,0) );
            $text->SetBackgroundColour( Wx::Colour->new('yellow') );
        }
    );

    $sizer->Add( $text, 0, wxALIGN_CENTRE | wxGROW | wxALL, 2, );
    $sizer->Add( $button, 0, wxALIGN_CENTRE | wxGROW | wxALL, 2, );
    $self->SetSizer( $sizer );
    $sizer->Fit($self);

    return $self;
}

1;

package App;

use strict;
use warnings;
use base 'Wx::App';

sub OnInit {
    my $frame = Frame->new();
    $frame->Show( 1 );
}

package main;

use strict;
use warnings;

my $app = App->new();
$app->MainLoop;
[download]

Regards, Stefan