Trouble referencing a Resource Dictionary that contains a Merged Dictionary

Answered a similar question here earlier, see Adding a Merged Dictionary to a Merged Dictionary question.

This is an optimization bug, see Microsoft Connect / DefaultStyleKey style not found in inner MergedDictionaries:

On the creation of every object in
XAML, if a default style is present
(i.e. style w/ a key of Type) that
style should be applied. As you can
imagine there are several performance
optimizations to make that (implied)
lookup a light weight as possible. One
of them is that we don’t look inside
Resource Dictionaries unless they are
flagged as “containing default
Styles”. There is a bug: if all your
default styles are nested in merged
dictionaries three levels deep (or
deeper) the top dictionary does not
get flagged so the search skips it.
The work around is to put a default
Style to something, anything, in the
root Dictionary.

So adding a dummy style to the root dictionary fixes this. Example

<Application x:Class="MyApp.App"  
                    Source="/CommonLibraryWpfThemes;component/Themes/Generic.xaml" /> 
            <!-- Dummy Style, anything you won't use goes --> 
            <Style TargetType="{x:Type Rectangle}" /> 

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