CODE EXAMPLE FOR CSHARP

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>