sub save_selected {
    my @check_boxes = @{ shift; };
    my $doc_nr = &Kephra::Document::_get_current_nr;
    for ( 0 .. $#check_boxes ) {
        if ( ref $check_boxes[$_] ne '' ) {
            if ( $check_boxes[$_]->GetValue ) {
               
 ...
            }
        }
    }
        ...
}