Clicking on the netscape icon (running netscape-communicator), with a Netscape window open now causes the original window to close, and a new one to open. This also happens with "ulrview" in mutt. This changed in 6.95, and is the same in 7.0. In 6.2 it used to open a new window (keeping the original one intact), which seems much better and friendlier :^)
Update: Hrm - wierd. I assume that netscape must be segfaulting sometimes - having restarted X several times (to try to find details for another bug), I seem able to startup new Netscape windows whilst keeping the original window. It seems a somewhat transient problem :(
I have not been able to reproduce this here.