I have a form class stored in DLL that has 2 tabbed pages. Page 2 has no objects on it. I reference the DLL in my project, and create a new form using "Inherits". In the new subclass I add some text objects to Page 2.

This works for a short while (minutes). I then inevitablely lose all textboxes on Page2. It certainly occurs if I make any modifications to the source code in the DLL.

Various versions of these errors appear suddenly as the textboxes dissappear:

Method System.CodeDom.CodePropertyReferenceExpression.AddRange not found.
Method System.CodeDom.CodePropertyReferenceExpression.ResumeLayout not found.
Method System.CodeDom.CodePropertyReferenceExpression.SuspendLayout not found.

I believe I'm losing the Tab Page formatting code as the form reverts to the parent class empty page 2. (The internal code creating objects remains, but the page visual representation dissappears and the errors occur)

I thought this occurred only when I rebuilt the base class DLL, but it has now happened twice while I was simply coding the subclassed form itself, and I was not in the .DLL code.

Has anyone else experienced this behaviour? Or have a clue about the problem here, or what I can to do work around this behaviour? How do I subclass tabbed forms without routinely losing the work?

Don Meuse