Hi all,

We have a custom form designer that is based on Microsoft's sample
available for download. There were few things missing in that sample
that we've added:
- IExtenderListService implementation for site class
- GetExtenderProviders() for site class that calls into class host
- our own design form, which is declared as: DesignForm : Form, with
the following attribute:
Designer("DesignerHost.Designers.DesignFormDesigner,
DesignerHost.Designers", typeof(IRootDesigner))
- our own form designer declared as DesignFormDesigner :
DocumentDesigner

Everything seems to work fine except serialization. It appears that
most of the newly created design form properties simply don't
serialize. After some extensive research we found the cause of the
problem, which appears to lie in Microsoft's design support classes.
Here's what happens:
- When our form designer is created, it calls into base.Initialize(),
which is followed by PreFilterProperties()/PostFilterProperties()
calls while it's still in base.Initialize()
- Right after those 2 calls DocumentDesigner().Initialize() adds 3
designer extenders (LocalizationExtenderProvider, etc.) to the site
- Next call to TypeDescriptor.GetProperties() for our designer
component fails to find previouselly cached component type reference
in its cache because number of extender providers is taken into
account when performing cache lookups (that's due to the previous item
I've just mentioned)!
- The above TypeDescriptor.GetProperties() resolution failure causes
our ITypeDescriptorFilterService.FilterProperties() implementation to
be called, which in turn calls into our designer
PreFilterProperties()/PostFilterProperties() for the 2nd time!
- That eventually calls into ComponentDesigner.PostFilterProperties(),
which swaps most of the cached properties types from
ReflectPropertyDescriptor to InheritedPropertyDescriptor
- During serialization,
InheritedPropertyDescriptor.ShouldSerializeValue() acts slightly
differently from ReflectPropertyDescriptor.ShouldSerializeValue(), but
enough to reject the value changes as not required serialization,
hence the problem

This is rather an advanced subject and I wouldn't be surprised if I
don't get many replies. I hope this makes sense and that good people
at Microsoft will be able to shed some light on it. I'd appreciate any
suggestions at this point. Thanks.

PS We use VS.NET 2003.