Google-docs – Keyboard shortcut for strike-through

The problem is for non-windows users I believe. Windows users use Ctrl + F and it works to open up the find interface. But when you're using a Command button with other systems, it seems that it is not registering the Command, just the f which "favorites" the message. Is that the issue you're having? Here is a list of the new keyboard shortcuts.

There is no way to disable them without going back. But if the problem I mentioned is the correct one, you might try de-activating selection of the current message. Push Esc first.

It is Shift+3 within a message for Mac.
It is the same in the inbox as well

1. You must move to the message with j/k
2. Select a message with x
3. Then press Shift+3

It could be that your keyboard layout is different.
Using a UK layout, it would be Option + 3 : ⌥ + 3, but this does not work (Not sure why).
You can also remap your keys with the Google Labs feature : Custom keyboard shortcuts