[ecfisa]

Hola arrayman.

Código Delphi [-]
...
type
  TScrollBox = class(Forms.TScrollBox)
  private
    procedure WMNCCalcSize(var Message: TMessage); message WM_NCCALCSIZE;
  end;
  
  TForm1 = class(TForm)
    ScrollBox1:  TScrollBox;
  ...

implementation

procedure TScrollBox.WMNCCalcSize(var Message: TMessage);
var
  Style: Integer;
begin
  Style:= GetWindowLong(Handle, GWL_STYLE);
  SetWindowLong(Handle, GWL_STYLE, Style or WS_HSCROLL ); // agrega: or WS_VSCROLL); para ver ambas 
  inherited;
end;
...

Un saludo.