When you connect to a machine via vnc, the system tray icon changes to alert the user that there is a remote connection, however, there is a registry key that can be used to hide the vnc icon, or change its icons so that is shows the same for monitored or unmonitored, thus there is no give away that somebody is remotly veiwing your work...
Copied from another forum:-
In HKEY_LOCAL_MACHINE\SOFTWARE\ORL\WinVNC3,
"DisableTrayIcon"=dword:00000001
An alternative and more drastic measure to prevent the VNC
icon from appearing in the system tray is to modify the
a registry entry specific to Windows itself. Making a mistake
in here could prevent Windows from ever working correctly again,
so please beware.
If VNC is running as a service, you can remove its service helper
key from the Windows registry. That is, via regedit, remove the
"WinVNC" value which can be found in one of these:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
or
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
or
HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Again, this is very risky. But it should work.
The third method of "hiding" the VNC tray icon requires some
developers tools: using a resource editor, modify the WinVNC
icon so that it will show the same icon both before and after
a client is connected.
Thanks to Michael Roland for the contribution!