writeText method
Overwrites selection with text
Implementation
void writeText( String text ) {
int pos = _textEditingController.selection.baseOffset;
_textEditingController.text.replaceRange(pos, pos, text );
_textEditingController.selection = TextSelection(baseOffset: pos+text.length, extentOffset: pos+text.length );
_setState();
_sendTextEvent( _textEditingController.text );
}