...Drag & Drop items from a TListBox to a TRichEdit?

function RECharIndexByPos(RichEdit: TRichEdit; X, Y: Integer): Integer;
var
  P: TPoint;
begin
  P := Point(X, Y);
  Result := SendMessage(RichEdit.Handle, EM_CHARFROMPOS, 0, Longint(@P));
end;


procedure TForm1.RichEdit1DragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
var
  P: TPoint;
begin
  // Check, if Source is ListBox1
  Accept := Source = ListBox1;
  if GetCursorPos(P) then
    with RichEdit1 do
    begin
      // Get the Index from Mouse Position
      P := ScreenToClient(P);
      SelStart := RECharIndexByPos(RichEdit1, P.X, P.Y);
      SetFocus;
    end;
end;

procedure TForm1.RichEdit1DragDrop(Sender, Source: TObject; X, Y: Integer);
begin
  // finally insert text at mouse position
  RichEdit1.SelText := ListBox1.Items[ListBox1.ItemIndex];
end;

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