There are no stupid questions - only stupid answers :-)
I've just described this effect a lot of times before.
The engine tries to look up the assembly and dictionary attached properties from the target object in the visual or logical tree. If this object is located in an island that can't be traced to the top level framework element (usually the main window) using the Parent properties, this approach failes and it needs these settings directly at the extension key.
I've just described this effect a lot of times before.
The engine tries to look up the assembly and dictionary attached properties from the target object in the visual or logical tree. If this object is located in an island that can't be traced to the top level framework element (usually the main window) using the Parent properties, this approach failes and it needs these settings directly at the extension key.