On Mon, Apr 15, 2019 at 11:00 AM Michael Van Canneyt via lazarus <lazarus at lists.lazarus-ide.org> wrote: > When you set Multiselect = True, the treeview (Linux, GTK) sends OnChange > messages with Nil node. > > procedure TCustomTreeView.OnChangeTimer(Sender: TObject); The name OnChangeTimer hints the handler is for a timer. Is it so? Juha