On ShellTreeListBox I'm using a simple StringFilterBase filter. When the filter is active and the filter text is for example "abc" and I move the following folder with its content
into the directory which is visible/filtered by the ShellTreeListBox, then Abcdefg_folder appears right in the filtered results view but its shown as an empty folder. When I clear/disable the filter then, Abcdefg_folder is not expandable. So its folder content was not added to the ShellTreeListBox.