This is related to a problem with how the security manager works on the IcedTea Web Plugin, so yeh nothing to do with LWJGL code. There is another bug report here
which highlights the issue in more detail. The IcedTea maintainers already have a fix for the LWJGL issue however they have not been applied it yet because they are waiting for some more security related architecture changes to go in before applying it.
Currently its aimed to be included in the IcedTea-Web 2.0 release, as shown by the RoadMap here