{
    # grub theme for koozali:
    #GRUB_THEME="/boot/grub2/themes/koozali/theme.txt"
    #GRUB_GFXMODE="1024x768"
    my $GrubTheme = $Sysconfig{'GrubTheme'} || 'koozali';
    my $GrubGFXMODE = $Sysconfig{'GrubGFXMODE'} || '1024x768';

    # remove if disabled
    if ($GrubTheme eq 'disabled') {
        @lines = map {
                s/^GRUB_GFXMODE.*//;
                s/^GRUB_THEME.*//;
                $_
        } @lines;
    }
    else {

        # change if line already there
        @lines = map {
                /^GRUB_GFXMODE/ && ! /="$GrubGFXMODE"/ &&  s/=".*"/="$GrubGFXMODE"/;
                /^GRUB_THEME/ && ! /="\/boot\/grub2\/themes\/$GrubTheme\/theme.txt"/ && s/=".*"/="\/boot\/grub2\/themes\/$GrubTheme\/theme.txt"/;
                $_
        } @lines;

        # add if line missing
        push @lines, 'GRUB_GFXMODE="'.$GrubGFXMODE.'"'  unless ( grep  /GRUB_GFXMODE/, @lines );
        push @lines, 'GRUB_THEME="/boot/grub2/themes/'.$GrubTheme.'/theme.txt"'  unless ( grep  /GRUB_THEME/, @lines );
    }
    "";
}

