>>You can automate the process of re-defining the class for existing comboboxes. You would just write a program that opens each SCX and looks for items based on the CBMM combobox class and change the class and class library for these items. USE MyForm.scx to look at the fields in the SCX. It's really pretty straightforward. You'll probably want to back up all of your forms before doing this just in case!
>>
>>>I want to change the behaviour of all my combobox. I want that after the user selects an option, the focus is given to the next control. Problems :
>>>
>>>1) I don't want to change a framework control, since I'll lose my changes when a new version comes.
>>>2) I can sub-class cComboBox, add my new features, but I'll have to change all Base Classes of all ComboBox boxes in all my forms.
>
>Is there any utility to do this ?

The class browser allows you to re-define a single item, but I don't think it allows this kind of wholesale change. There may be something in the file section here. I you look at the structure of the SCX you'll see that it wouldn't be hard to write your own utility to do this.