Question

Does DependencyProperty.OverrideMetadata() overrides the PropertyChangedCallback too ?

Answer 1

Taken from here: http://msdn.microsoft.com/en-us/library/ms597491.aspx

The supplied metadata is merged with the property metadata for the
dependency property as it exists on the base owner. Any
characteristics that were specified in the original base metadata will
persist; only those characteristics that were specifically changed in
the new metadata will override the characteristics of the base
metadata. Some characteristics such as DefaultValue are replaced if
specified in the new metadata. Others, such as
PropertyChangedCallback, are combined.