input text from ime(EditableText)

https://github.com/kyorohiro/hello_skyengine/tree/master/edit_text

// following code is checked in 2016/01/13
import 'package:flutter/widgets.dart';
import 'package:flutter/painting.dart';
import 'package:flutter/rendering.dart';
import 'dart:ui' as sky;
import 'package:flutter/services.dart';

main() async {
  print("------------------");
// setup keyboard
//  KeyboardServiceProxy pService = new KeyboardServiceProxy.unbound();
//  await shell.requestService(null, pService);
//  Keyboard keyboard = new Keyboard(pService.ptr);

// setup editable text
  Color textColor = const Color.fromARGB(0xaa, 0xff, 0, 0);
  sky.Offset offset = new sky.Offset(0.0, 0.0);
  TextStyle textStyle = new TextStyle(fontSize: 50.0, color: textColor);
  EditableString st = new EditableString(text: "test:",
  onUpdated: () {},
  onSubmitted:(){print("onSubmit");});

  EditableText text = new EditableText(
      key: new Key("editabletext"),
      value: st,
      style: textStyle,
      scrollOffset: offset,
      focused: true,
      cursorColor: textColor,
      onContentSizeChanged:(Size newSize) {print("onContentSizeChange");}
      );
  Center r = new Center(child: text);
// run & show ime
  runApp(r);

  keyboard.show(st.stub, KeyboardType.TEXT);
  keyboard.service.setText("");
  keyboard.service.setSelection(0, 0);
}