Use this code for an Edit's OnKeyPress event.

   void __fastcall TForm ::Edit KeyPress(TObject *Sender, Char *Key)
   {
      if (Key == "# 3")
      {
         SelectNext(dynamic_cast (Sender), true, true );
         Key = "#0";
      }
   }

   void __fastcall TForm ::Edit KeyPress(TObject *Sender, Char *Key)
   {
      if (Key == "# 3")
      {
         SelectNext(dynamic_cast (ActiveControl), true, true );
         Key = "#0";
      }
   }