Emerson,
My treeview control hooks into the resize of the parent container through BINDEVENT(). IF the parent (in the case the Outlook2003Bar.Panel) resizes then the treeview changes size to match it. I made no references to the any specific classes such as the splitter to keep my control completely self contained. If I did it correctly any changes to the Outlook2003Bar should be very transparent.

The version I make "public" is definitely going to be a wrapper for the MS TreeView Control 6.0 SP4. I used the DBI-Tech ctTree initially because I am rolling it into a production application and I didn't realize how reusable the control was going to be. Now that I have seen it's potential I am switching it to the native control and plan on making it available to everyone once I finish it up.