How to update Collapse/Expand Node Picture in TADVTreeView

ExpandCollapse

On attached image please note Open Folder and Closed Folder icons towards the bottom. How do I achieve this with TADVTreeView ?.

Have not tried the following because I don't know how to assign to TAdvtBitmap. Do I use a PictureContainer ? Do I use a bitmap ?

procedure TForm1.AdvTreeView1BeforeDrawNodeExpand(Sender: TObject;
AGraphics: TAdvGraphics; ARect: TRectF; AColumn: Integer;
ANode: TAdvTreeViewVirtualNode; AExpand: TAdvBitmap; var AAllow: Boolean);
begin
end;