Virtual treeview place the vertical scrollbar on right side in the RightToLeft bidimode

Is it possible to place the vertical scrollbar of Virtual treeview on right side in the RightToLeft bidimode and place it on left side in the LeftToRight mode?

Solution

Why not? If TVirtualTreeView uses system scrollbars it could be done with setting appropriate extended style.

procedure TForm1.Button2Click(Sender: TObject);
const
  LSB = WS_EX_LEFTSCROLLBAR;
var
  ExStyle: LONG_PTR;
begin
  ExStyle := GetWindowLongPtr(AVTV.Handle, GWL_EXSTYLE);

  // Check if RTL alignment specified for you component
  if AVTV.BiDiMode = bdRightToLeft then
    begin
      // If so, then exclude LSB-constant and allow Windows place 
      // scrollbar on the right side of window
      if (ExStyle and LSB) = LSB then
        SetWindowLongPtr(AVTV.Handle, GWL_EXSTYLE, ExStyle and not LSB);
    end
  else
  if AVTV.BiDiMode = bdLeftToRight then
    begin
      // The same as operation above but for LTR order
      if (ExStyle and LSB) <> LSB then
        SetWindowLongPtr(AVTV.Handle, GWL_EXSTYLE, ExStyle or LSB);
    end;
end;

LSB constant is used to make code more compact in post.