>The problem is probably that you have an object instantiated that reference a class in the classlib - you can't change the classlib while an object referencing something in the classlib is active. If you have a classlib Lib1.VCX, with a subclass of a textbox called txtSub1 and a ComboBox cboSub1 in it, and a second class library Lib2.VCX containing a textbox subclass txtSub2 whose parent class is txtSub1, you can't change any classes in either Lib1 or Lib2 if something based on txtSub2 is instantiated. You can't go back and change your parents...

Hi Ed
I know that if a have a instance of a class in memory i can't modify the class.
But what i said is if you don't have a instance in memory you just modify the class with {modify class} and after that you can't delete the library ???

you have a classlibrary lib1.vcx this class contain 2 class
class1 -> textbox -> Name = cBaseTextBox
class2 -> cBaseTextBox -> Name = cTextBox

Exemple at command line:

CLEAR ALL (no instance in memory)
MODIFY CLASS cTextBox of lib1.vcx
DELETE FILE lib1.vcx (File is in use)

Do you have an idea if i want delete the classlibrary whitout use the command Clear All ?

Thank's a lot for your help
It's for a litle tools i made if you find the way i can do this
i will put your name on with mine and i send you a copy.