ShellTreeView Node Expand: second expand repopulates the node. And it is slower than the first one.

Lazarus/FPC Version: <Lazarus 2.2.4 (rev lazarus_2_2_4) FPC 3.2.2 x86_64-win64-win32/win64__>
Operating System: Windows x64
CPU / Bitness: 64

What happens

When opening a collapsed node the second time, it will be populated again, and it takes twice of the time.

And: a selection of a sub-node previously being done will go lost

What did you expect

I expect

when re-expanding the node, this is done instantly without clearing/repopulating the node No more node population is done again redundantly. And certainly not it should take twice the time.

I'd expect aht an already populated node can be re-expanded instantly.

For which reasons not do this code change? Wherefor a repopulation should be good for?

Steps to reproduce

Drop a ShellTreeView on a form
Run the application and navigate to the folder (drivename:)\Windows\WinSxS
Expand the node (fast!)
Collapse the node
Expand the node again. This takes at least twice as long. Slow!

Do the change described below (ShellCtrls.pas) and run the node's expand - collapse - expand again. Notice the time difference.

function TCustomShellTreeView.CanExpand(Node: TTreeNode): Boolean;
var
  OldAutoExpand: Boolean;
begin
  Result:=inherited CanExpand(Node);
  if not Result then exit;
  OldAutoExpand:=AutoExpand;
  AutoExpand:=False;
  BeginUpdate;
  try
    Result := True;
    if Node.Count = 0 then begin  // --- Added. Do it only if node is not yet populated
        //Node.DeleteChildren;    // --- Not needed regarding the condition
        Result := PopulateTreeNodeWithFiles(Node, GetPathFromNode(Node));
    end
    else  Result := True;        // --- Added    
    AutoExpand:=OldAutoExpand;
  finally
    EndUpdate;
  end;
end;

Side-effects of this change i couldn't detect so far. Might there be any ??

Supplementary note: i'd expect that when selecting a subnode "Sub1" beyond parent node "Parent1", that when i collapse Parent1 by click on the expand sign, and re-expand it again, the previous selection marker on Sub1 is preserved. Using the change, it stays preserved. By the current behaviour (= sub nodes cleanup) it goes lost. Not ok. Please keep my selection!