Good luck with getting NoMachine to even admit there's a problem...

I don't know if you've noticed, but the NX client doesn't handle the X backing
store correctly. When I tracked down the reason and informed NoMachine of this
their answer was pretty much of the form "this is how we've interpreted the
meaning of backing store, and we're not changing it" even though it is
blatantly obvious that their interpretation doesn't meet with the requirement.

They basically changed the way it operates, taking away the responsibility of
maintaining the backing store from the server and placing it on the client to
handle all expose events. But this is exactly what the backing store is
supposed to do. The reason they've done this (they actually have to modify the
X source code to break it) is to improve performance.

In their eagerness to optimize the X protocol they've actually broken some of
its functionality. But they won't admit they've broken it and
instead "interpret" how it should work to meet with how their code actually
works. So, they clearly regard how fast NX works as more important than how
correctly it works.

I always run as a desktop. I don't like floating windows.

If I use floating windows then the same problem arises with the Windows client,
but works ok with the Linux client.

We don't use the NoMachine NX server as their licensing fees are exorbitant.
Instead we use freenx, and I've build my own binaries from the NX server open
source.