I used EVL to create to specify metamodel constraints to validate models created using a GMF editor.
When I try to validate a model, I often get the error "Decorator refresh failure". It happens often when I have a large model, but even with small models, sometimes I also get this error.
The model is validated correctly, but when I get this error, the error/warning markers are not updated (I have to close and reopen the diagram to update the markers).
I remember the error is a NullPointerException in method refreshDecorators(String viewId, Diagram diagram), from class *.diagram.providers.*ValidationDecoratorProvider (from the .diagram project generated automatically by GMF).
Unfortunately I didn't save the error log, and I'm unable to reproduce the error now... (It's weird, as I had have this problem dozen of times before.)
When I get the error again, I'll put the log here.