As you see in the code I posted I use form and commandbutton base classes and I don't have any access method. I use VFP 6.0 SP3 ver. 06.00.8492.00. The same code run on 06.00.8167.00 without SP3 fires the Width_Assign method again.
_Assign method for a form caption property, for example, and for a user defined property works normally. My problems are Width and Height properties of a form or a container.