Hi

1. Define one Class X with properties 'Prop' PUBLIC or PROTECTED.
2. Use 'Prop' on Code of Class.
( typical is the case of one class to sell or to use from others )

3. SubClassing Class X to Y.
4. On Y uses Code of X
5. On Y HIDDEN 'Prop'

Result:
Class X don't see 'Prop'

Consequence -> Subclassing Black Box has BIG Limits.

*****************
Simple example:

PUBLIC oform1

oform1=NEWOBJECT("form1")
oform1.Show
RETURN

DEFINE CLASS form1 AS form

Caption = "bug hidden ?"
Name = "Form1"

ADD OBJECT txclass1 AS txclass WITH Left = 100, Top = 10

ADD OBJECT txsubclass1 AS txsubclass WITH Left = 89, Top = 115, Name = "Txsubclass1"

ENDDEFINE

DEFINE CLASS txclass AS textbox

Tag = "TagValue"
Name = "txclass"

PROCEDURE Click
MESSAGEBOX(this.tag)
ENDPROC

ENDDEFINE

DEFINE CLASS txsubclass AS txclass

Name = "txsubclass"
HIDDEN tag

ENDDEFINE

Click on txclass1 and txsubclass1.

Fabio