The Keyboard should display all of the corresponding key labels on each key, considering the different modifiers that may affect them. However, this should only be done where space allows it, as the keys may become unreadable otherwise.

An example; instead of simply:
+---+
| 1 |
+---+
the "1" key should show, for a US keyboard layout:
+---+
| ! |
| 1 |
+---+