Why BeforeUpdate Event N/A in my TextBox class?

After including in my new class module the following statement:

Public WithEvents tbThis As MSForms.TextBox

I then select tbThis from the Object drop-down in VBE, after which many (but not all) TextBox events are available in the corresponding procedure drop-down. In particular, I'd like my tbThis class to handle the BeforeUpdate event, but it is not available.

I've tried modifying my WithEvents statement to refer simply to TextBox instead of MSForms.TextBox, but then the tbThis class is no longer available from the object drop-down.

Is it possible to define a TextBox class that can handle ALL of the TextBox events, or at least the Change and BeforeUpdate events? If so, what do I need to do differently to get access to these elusive events?

Thanks very much for any help,
Bruce Reid