wpf resource dictionary
<Window.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="ResourceDictionary.xaml"/>
<ResourceDictionary Source="pack:
//application:,,,/WpfExternalDictionary;component/View/ResourceDictionary.xaml"/>
</ResourceDictionary.MergedDictionaries>
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
<System:Double x:Key="ButtonWidth">80</System:Double>
</ResourceDictionary>
</Window.Resources>