Plone 2.x to Plone 3.x upgrade

Recently I am working on plone 2 to plone 3 upgrading. The following codes I think is commonly used in many cases, that need to be change as following:

Old	New
from Products.CMFCore.CMFCorePermissions import AddPortalContent	try: from Products.CMFCore.permissions import AddPortalContent except ImportError: from Products.CMFCore.CMFCorePermissions import AddPortalContent
from Products.AddRemoveWidget.ComboBoxWidget import ComboBoxWidget	from Products.Archetypes.Widget import SelectionWidget
import Products.CMFCore import CMFCorePermissions	try: # New CMF from Products.CMFCore import permissions as CMFCorePermissions except ImportError: # Old CMF from Products.CMFCore import CMFCorePermissions
All text ComboBoxWidget	Converted into SelectionWidget
import Products.CMFCore.CMFCorePermissions as CMFCorePermissions	try: # New CMF from Products.CMFCore import permissions as CMFCorePermissions except ImportError: # Old CMF from Products.CMFCore import CMFCorePermissions
from Products.CMFCore.CMFCorePermissions import setDefaultRoles	try: # New CMF from Products.CMFCore.permissions import setDefaultRoles except ImportError: # Old CMF from Products.CMFCore.CMFCorePermissions import setDefaultRoles

I am expecting your contribution to add more like this type of changes during plone 2 to plone 3 upgrade.

Thanks,
Sakib