I just noticed a spurious entry in the Structure Window for one of my Groovy source files. It just says "Invalid" and has no icon. Clicking it (even double-clicking, though I have the "Autoscroll to Source" option enabled for the Structure window) had no effect.
When I switched to a different file and then back, it was gone. I'm not sure if it was in place of an entry that should have been there or if it was in addition. I was going to check, but it disappeared before I could.
I'm using JetGroovy 0.1.11420 on Selena build #7323.