dict-like object for looking up commands from keystrokes
Default values (key: command):
'tab': 'next selectable',
'ctrl n': 'next selectable',
'shift tab': 'prev selectable',
'ctrl p': 'prev selectable',
'ctrl l': 'redraw screen',
'esc': 'menu',
'up': 'cursor up',
'down': 'cursor down',
'left': 'cursor left',
'right': 'cursor right',
'page up': 'cursor page up',
'page down': 'cursor page down',
'home': 'cursor max left',
'end': 'cursor max right',
' ': 'activate',
'enter': 'activate',
Return a new copy of this CommandMap, likely so we can modify it separate from a shared one.