procedure TForm1.Button1Click(Sender: TObject);
var
 R : TRect;
 Linkm:integer; { Linker Marge }
 Rightm:integer; { Rechter Marge }
begin
 Linkm:=20;
 Rightm:=10;
 
 R := Memo1.ClientRect;
 R.Left:=R.Left + Linkm;
 R.Top:=R.Top + 2;
 R.Bottom:=R.Bottom - 2;
 R.Right:=R.Right-Rightm;
 SendMessage(Memo1.Handle, EM_SETRECT, 0, Longint(@R));
end;