The issue occurs with the following set up:

- NoMachine Player for Windows.
- Any NoMachine Server product for Linux supporting custom, floating window sessions.

Steps to reproduce:

1. From the Windows client, start a floating window custom session (A) to run gnome-terminal on the Linux server.
2. From the same client, run a second session custom session (B) with settings identical to A.
3. Try to click or type anything in the gnome terminal owned by session B: all events are sent to session A instead.

The problem does not change if sessions A and B run on the same server or different servers.
No change also if servers are from NoMachine version before the 4.