AdvGridDropDown.DropDownWidth

How i get a new/actual AdvGridDropDown.DropDownWidth after resize?

You can do this with:

procedure TForm5.FormCreate(Sender: TObject);
begin
  advstringgrid1.AdvGridDropDown.OnDropUp := AdvGridDropDownDropUp;
end;

procedure TForm5.AdvGridDropDownDropUp(Sender: TObject; Cancelled: Boolean);
begin
  Caption := inttostr( AdvStringGrid1.AdvGridDropDown.DropDownSize.cx);
end;

Yes, thank you.