use vars qw(%keybinding);

%keybinding = (
  ... default keybinding
);

my @user_bindings = do 'user_keybinding.pl';
while (@user_bindings) {
  my ($k,$v) = splice @user_bindings, 0, 2;
  $keybinding{$k} = $v;
};

sub key_down_filter    {
  my ($sci_frame, $event) = @_;
  my $key = $event->GetKeyCode;
  if ($event->AltDown) {
    $key = "a$key";
  };
  # same for shift, ctrl, meta, footpad, escape

  if (exists $keybinding{$key}) {
    # dispatch
    $keybinding{$key}->($sci_frame,$event,$key);
  };
};