HandyControl/src/Shared/HandyControl_Shared/Themes/Lang.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:langs="clr-namespace:HandyControl.Properties.Langs">

    <langs:LangProvider x:Key="Langs"/>

</ResourceDictionary>