We were discussing VNC clients on IRC recently, and the fact that the Linux 
vncviewer from TightVNC doesn't have the icon in the upper left corner that 
the docs refer to, the icon that gives you a menu to do things line send 
Ctrl-Alt-Delete.

KRDC runs in full-screen mode and sends all keystrokes, so you can just press 
Ctrl-Alt-Delete, but the only way out of Full Screen is with the mouse.

Today I found that you can access the function menu in TightVNC by pressing 
F8, so it is still my application of choice for this.