QML实现-按钮点击变色功能

import QtQuick 1.0Rectangle {    width:400    height:400    Rectangle {        id:btn        width: 122        height: 30        color: "red"        Text {            text: "Welcome to China"        }        MouseArea {            anchors.fill: parent            //onClicked: btn.state == 'clicked' ? btn.state = "" : btn.state = 'clicked';                  onContainsMouseChanged: btn.state == 'clicked' ? btn.state = "" : btn.state = 'clicked';        }        states: [            State {                name: "clicked"                PropertyChanges { target: btn; color: "blue" }            }        ]    }

onContainsMouseChanged是MouseArea中的响应方法，关于QML中的元素查询，官方地址：
http://doc.qt.nokia.com/4.7-snapshot/qdeclarativeelements.html