xmlns:esriSymbols="clr-namespace:ESRI.ArcGIS.Client.Symbols;assembly=ESRI.ArcGIS.Client"> <esriSymbols:MarkerSymbol x:Name="SomeCustomMarkerSymbol"> <esriSymbols:MarkerSymbol.ControlTemplate> <ControlTemplate> <Grid x:Name="RootElement"> <!-- Add any content here. Button, Image, Button with Image Content, Custom Menu, etc...--> <Button Content="A Button I Added!"/> </Grid> </ControlTemplate> </esriSymbols:MarkerSymbol.ControlTemplate> </esriSymbols:MarkerSymbol>