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);
}