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if Chr(Key)=',' then ...					

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if key = 188; // rausgekriegt mit showmessage(inttostr(key));					

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function GetCharFromVKey(vkey: Word): string;
var
  keystate: TKeyboardState;
  retcode: Integer;
begin
  Win32Check(GetKeyboardState(keystate));
  SetLength(Result, 2);
  retcode := ToAscii(vkey,
    MapVirtualKey(vkey, 0),
    keystate, @Result[1],
    0);
  case retcode of
    0: Result := ''; // no character
    1: SetLength(Result, 1);
    2:;
    else
      Result := ''; // retcode < 0 indicates a dead key
  end;
end;

....

if GetCharFromVKey(key) = ',' then ....