>>Then COMCTL32.OCX is enough. It also must be included into the project file
>
>The project file?
>
>Do you mean adding this into the Others file?

Yeah, that's what I did.
I didn't play with it much, I just did, as they say in TreeView Help. This is it:

Distribution Note The TreeView control is a 32-bit custom control that can only run on Windows 95 or Windows NT 3.51 or higher. The TreeView control is part of a group of custom controls that are found in the COMCTL32.OCX file. To use the TreeView control in your application, you must add the COMCTL32.OCX file to the project. When distributing your application, install the COMCTL32.OCX file in the user's Microsoft Windows SYSTEM directory.