Question

Is it possible to add one resource dictionary into other one?

Answer 1

In Dictionary2.xaml define MergedDictionaries (right after the opening ResourceDictionary tag):

<ResourceDictionary.MergedDictionaries>
    <ResourceDictionary Source="/Path/to/Dictionary1.xaml" />
</ResourceDictionary.MergedDictionaries>

there’s a catch: each time you merge dictionaries you effectively create a copy of the merged dictionary. And it’s recursive – if you have Dict3.xaml and Dict4.xaml that both load Dictionary2.xaml, you will have three instances of Dictionary1.xaml created

The solution is a SharedResourceDictionary. The implementation in the tutorial should be seen as a starting point and will probably need some level of tweaking – depending on use scenario. Google “wpf SharedResourceDictionary” for some gotchas and solutions.

From answer to this question by XAMeLi