[lazarus] TNoteBook probems Fixed

[Gertjan Schouten]

> * A control should never be part of its own controls collection. In my
> debugmessages I see constructions like:
> [TWinControl.Remove] TBUTTON --> Remove: TBUTTON ()
> [TWinControl.Insert] TPAGE --> Insert: TBUTTON ()
> and it looks like the parent of TBUTTON was TBUTTON itself. 
> Something similar: A form has no parent and while looping through the
> controls collection, you'll find the form as Controls[0]

Parent in TForm has only meaning if the form is an MDIChild.
Setting the FormStyle of a Form to fsMDICHILD sets the Parent 
property to Application.MainForm, otherwise Parent is always NIL




Gertjan