...but, strangely enough, only in some circumstances. To reproduce: 1) Set client to "Near current screen size" without fullscreen 2) Connect to a system that requires you to enter a OTP After the OTP window closes, the following error appears at the console (the hex value differs): X_GetWindowAttributes: BadWindow (invalid Window parameter) 0x540021e On Gnome 2 there are no ill effects of this, however on Gnome 3 the session appears to freeze until vncviewer is moved or focus is switched.