Empfänger bei WM_DROPPFILES unterscheiden

[Luckie]

Leider liefert IsDragPointInside immer False.

Delphi-Quellcode:

function TfrmSteganosaur.IsDropPointInside(const aDropPoint: TPoint; const aControl: TControl): Boolean;
begin
  Result := PtInRect(aControl.ClientRect, aControl.ScreenToClient({Self.}ClientToScreen(aDropPoint)));
end;

procedure TfrmSteganosaur.AppMessage(var Msg: Tmsg; var Handled: Boolean);
const
  BufferLength: word = 255;
var
  DroppedFilename: string;
  FileIndex: Word;
  QtyDroppedFiles: Word;
  pDroppedFilename: array[0..255] of Char;
  DropPoint: TPoint;
begin
  if Msg.Message = WM_DROPFILES then
  begin
    FileIndex := $FFFF;
    QtyDroppedFiles := DragQueryFile(Msg.WParam, FileIndex, pDroppedFilename, BufferLength);
    for FileIndex := 0 to (QtyDroppedFiles - 1) do
    begin
      DragQueryFile(Msg.WParam, FileIndex, pDroppedFilename, BufferLength);
      DroppedFilename := StrPas(pDroppedFilename);
      DragQueryPoint(Msg.WParam, DropPoint);
      if IsDropPointInside(DropPoint, edtCarrierFile) then
        edtCarrierFile.Text := DroppedFilename
      else if IsDropPointInside(DropPoint, edtTrailerFile) then
        edtTrailerFile.Text := DroppedFilename;
    end;
    DragFinish(Msg.WParam);
    Handled := true;
  end;
end;