Linux F1 KeyDown got 255

[apeoperaio]

Dear all,

lazarus 1.4.4 fpc 2.6.4
Under linux VirtualBox if I launch my application and press F1 I got key =255 instead key = 112

procedure TfrmMainMenu.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  // check for F1
  if (Key = VK_F1) then
  begin
    //dosomething
  end;
end;

why?

Lazarus Ide seems to properly detect F1. My application not.
Analogously if I press
a
I got 141 that is
C octal escaped UTF-8: \141
as reported in character map in ubuntu.

Any hint?
Andrea Mauri