The "lineedit" library provides a
 quick way to implement nice line
 editing into applications.

It requires the user to store the
 line and the cursor position for the
 line, which allows the user to
 implement any additional logic for
 the application.

(To clarify, this implies that the
 library's functions are stateless.)

The functions are as follows:

draw = function (sW, line, curX, rX):
 Returns the spantext.

sW is the width of the area.
line is the safeTextFormatted text.
curX is the cursor in screen units
(usually done as part of the text
 formatting)
This is optional, and if not provided
 the cursor will not be shown.
rX is an optional camera override.
If not provided, the cursor will be
 used; if that is not provided, then
 the left side will be shown.

clamp = function (line, curX):
 Returns curX clamped to the line's
  length (does not check for < 1).

key = function (ks, kc, line, curX):
 Performs something.

ks, if truthy, is the unicode.char
 of the key event key character.
kc is the key event keycode.
(If feeding in clipboard characters,
 use 0 here.)

line is the text.

This returns three values, any of
 which or all of which may be nil for
 a 'no effect' response:

The new line text, 'lT'.
The new curX, 'lC'.
The extended action, 'lX'.

The following extended actions exist:

"l<": The cursor should be warped to
 the end of the previous line, if one
 exists (if not, do nothing)

"l>": The cursor should be warped to
 the start of the next line, if one
 exists (if not, do nothing)

"w<": This line should be welded to
 the previous line, and the cursor
 should be placed at the weld point.

"nl": The Enter button was pressed.

-- This is released into
 the public domain.
-- No warranty is provided,
 implied or otherwise.