Server editor complains about wrong runtime folder even if fixed

I had a runtime and server adapter set up for eap 6.4. I deleted the server on the disk. When I opened the server editor, I was shown a red message in the status bar:
The server's runtime folder does not exist: ......
So far so good.
So I unzip eap 6.4 somewhere else, clicked Runtime Environment in the server editor, and pointed the runtime to the new correct directory. Then I saved the editor. But the error message in the status bar still won't go away. I have to close the editor and then open it again, then the message no longer shows up.