Author: Tomas Rutkauskas

Is there a way to let a TComboBox do incremental search in its drop down list? 
Currently it uses only the first letter so if multiple items start with the same 
letter it's not very useful.

Answer:

Create a new Combo inherited from class(TcustomComboBox) and change the Change 
Event to the following few lines:

1   {...}
2   protected
3   
4   procedure Change; override;
5   {...}
6   
7     procedure TExtComboBox.Change;
8     var
9       str: string;
10      Index: Integer;
11    begin
12      inherited Change;
13      str := Text;
14      if (FLastKey = VK_DELETE) or (FLastKey = VK_BACK) then
15      begin
16        SelStart := Length(str);
17        SelLength := 0;
18        Exit;
19      end;
20      {try to find the closest matching item}
21      Index := Perform(CB_FINDSTRING, -1, LPARAM(str));
22      if Index <> CB_ERR then
23      begin
24        ItemIndex := Index;
25        SelStart := Length(str);
26        SelLength := Length(Items[Index]) - SelStart;
27      end
28      else
29        Text := str;
30      {call standard event}
31      if Assigned(FOnChange) then
32        FOnChange(Self);
33    end;
34  end.