The following keypad configuration is broken by default:
* (major) There are no distinguished Ctrl-Del/Home/End escape sequences (although there are Ctrl-modified sequences for other keypad keys).
* (major) The keypad middle key ("5", KP_Begin) is ignored, it should be mapped to ^[[E , ^[[1;5E etc.
* (minor) Escape sequences for Alt-Del/Home/End are inconsistent with those for other keypad keys with Alt.
Even using $HOME/.mlterm/key the following cannot be remapped:
* (major) Alt-Control-F1...F4,
* (medium) Keypad keys with Shift,
* (major) Home, End, KP_Home, KP_End, especially with modifiers (which cannot be added thus).