Nothing but controls...
I cannot imagine my apps w/o treeview or progressbar or similar controls. Thus I'm forced to use MS Common Controls 6.0 ActiveX library. It is much less powerful than .NET WinForms controls, has known bugs and there is no sign of possible update. There are also common problems in using ActiveX controls with VFP.
I like VFP. The platform is especially useful for technologies I develop. It is so great to integrate data, UI and communication in one relatively lightweight application but... Every time I add ActiveX control I got a problem with it. That's why I'm thinking about platform w/o need for ActiveX at all.