List ALL TAGS command when creating/editing POST

It would be good to be able to list ALL TAGS when you are in the edit screen for a POST.

The logic here is that we have a wide array of topics we want to TAG, my concern is that the people who are creating the content may not remember the 'exact' match for the TAG, so to be able to see the list may help them be creative.

Perhaps something similar to a down arrow press whilst in the TAG field - to display all and of course when you start typing this list reduces with the same behaviour that we have now, or a wildcard symbol, this is less desirable as it can lead to the need to backspace and replace once a TAG has been decided upon.

Many thanks.
Graham