Lava is still not fixed completely, meaning I can queue buildings on it, and F2 shows it can be built on. Instead, the fix seems to be some kind of hack that disables the build process when it's about to start. But this is confusing, would it not be possible to make lava behave like lava, and let F2 show the actual build possibility.
Look at this image for example.
References:
http://springrts.com/mantis/view.php?id=1227