Simple keyboard functions:
| KeyRead | Wait for and read keystroke. |
| KeyWait | Wait for but do not read keystroke. |
| KeyFlush | Clear all keystrokes from buffer. |
| KeyPreview | Check for and get keystroke leaving it in the buffer. |
| KeyShiftState | Return current keyboard control key shift status. |
| KeyPressed | Test if keystrokes are waiting. |
| KeyNotPressed | Test if keystrokes are not waiting. |