a copy can be disabled even when clicking Edit | Copy, it appears a disabled item.
a Select of Text can also be disabled.
Stopping Refresh function is useful for example to prevent a form from being submitted twice.
there are scripts that can for example when pressing Control+H takes you to the Home Page, and so on.. that's what I meant by assigning a certain function to a certain Key.
Control+C can be disabled by a JavaScript Code.
I didn't say F5 can be disabled, I am just thinking in a load voice.