How to search a VirtualStringTree in Delphi without using Edit?

I have VirtualStringTree with some items and I want to implement a feature similar to what a ComboBox has.

It works like this: when pressing a certain letter it should select the first item of the grid, as I press the same letter it goes through the other items that start with it. But if I start typing a word it should select the item corresponding to the one I typed.

Ex: If I press the letter f once it will select the first item that starts with the letter f . If I press it three times, you should select the third item that starts with the letter f .

But if I quickly type for it should select the item that starts with for , for example fornecedor

What I have been able to do so far is to select the item if I press a letter, but it does not go through all the items as I need them and it does not work if I type the excerpt of a word.

Follow the search code:

procedure TfrmGrid.SearchForText(Sender: TBaseVirtualTree; Node: PVirtualNode; 
Data: Pointer; var Abort: Boolean);
var
  NodeData: PPonteiro;
begin
  NodeData := PPonteiro(vtvGrid.GetNodeData(Node)^);
  // Interrompe a pesquisa caso encontre um nó com o texto correspondente
  Abort := AnsiStartsText(string(data), NodeData.ITEM);
  if vtvGrid.GetFirstSelected = Node then
   Abort := False;
end;

What goes in KeyPress of VirtualStringTree :

procedure TfrmGrid.vtvGridKeyPress(Sender: TObject; var Key: Char);
var
  foundNode : PVirtualNode;
begin
  inherited;
  foundNode := vtvGrid.IterateSubtree(nil, SearchForText, Pointer(Key));

  if Assigned (foundNode) then
  begin
    vtvGrid.FocusedNode := foundNode;
    vtvGrid.Selected[foundNode] := True;
  end;
end;