Add hook / callback when cursor moves when entering raw_input?

Question

Add hook / callback when cursor moves when entering raw_input?

I am trying to write a syntax highlighted version of an interactive interpreter.

Here is what I still have that works quite well (uses blessings and pygments ) ...

import code
import readline
import threading
import blessings
from pygments import highlight
from pygments.formatters import TerminalFormatter
from pygments.lexers import PythonLexer

def check_line():
    global current_line
    try:
        while True:
            line = readline.get_line_buffer()
            if line != current_line:
                current_line = line
                do_colour()
    except:
        pass

def do_colour():
    global terminal

    raw_line = readline.get_line_buffer()
    line = highlight(raw_line, lexer, formatter)[:-1]

    with terminal.location(x = 4):
        print line,

    readline.redisplay()

current_line = ''
terminal = blessings.Terminal()
lexer = PythonLexer()
formatter = TerminalFormatter()
console = code.InteractiveConsole()

colour_thread = threading.Thread(target=check_line)
colour_thread.setDaemon(True)
colour_thread.start()

console.interact('')

It colors the lines as they are entered ...

Problems:

In this case, a separate thread is used to check the employment for changes in the line (I think it could be using the whole kernel).
If you move the cursor backward along the line and then move it to the right, the terminal redraws the character that was simply not selected and does it in white

, , / - ? stdin , - raw_input, ?

P.S ("""like this""") , .

Edit:

, , ...

import code, ctypes, readline, blessings, signal, threading
from pygments import highlight
from pygments.formatters import TerminalFormatter
from pygments.lexers import PythonLexer

def slight_delay():
    threading.Timer(0.001, draw).start()
    return 0

def draw():  
    raw_line = readline.get_line_buffer()
    line = highlight(raw_line, lexer, formatter)[:-1]

    with lock:
        with terminal.location(x = 4):
            print line,
        readline.redisplay()

def keyboard_interrupt(c, frame):   # Ctrl-C throws in C code otherwise
    pass

callback = ctypes.PYFUNCTYPE(ctypes.c_int)(slight_delay)
hook_ptr = ctypes.c_void_p.in_dll(ctypes.pythonapi,"PyOS_InputHook")
hook_ptr.value = ctypes.cast(callback, ctypes.c_void_p).value
signal.signal(signal.SIGINT, keyboard_interrupt)

terminal = blessings.Terminal()
lexer = PythonLexer()
formatter = TerminalFormatter()
console = code.InteractiveConsole()
lock = threading.Lock()

console.interact('')