wpf - XAML - MergedDictionaries throwing XmlParseException "item has already been added". Why? -
    i have following, easy reproduce problem: i'm creating xaml application uses resources file. way go create mergeddictionaries-tag merge local , global resources, this:   <window> <window.resources>     <resourcedictionary>         <resourcedictionary.mergeddictionaries>             <resourcedictionary source="path.to.xaml.file"/>             <resourcedictionary>                 <style targettype="{x:type border}" x:key="typeblock">                  </style>                 <style targettype="{x:type border}" x:key="setblock">                  </style>             </resourcedictionary>         </resourcedictionary.mergeddictionaries>     </resourcedictionary> </window.resources> .... </window>   this little piece of code crash if run it:   item has been added. key in dictionary: 'system.windows.controls.border'  key being added: ...