We now use javadoc9 to generate 
http://gee.cs.oswego.edu/dl/jsr166/dist/docs/
The lower left frame is called "All classes".  If I click on one of those class names, the class javadoc is displayed, but in the same small lower left frame, and not in the "main" frame on the right as one would expect.

OTOH, if you first click on a package in the upper left, and then select one of the classes in the lower left, then it is displayed as expected in the main frame on the right.

We believe this is a regression.