popupWindow初始化完成
button背景drawable 一般设置法
<item android:state_window_focused="false" android:state_enabled="false"
android:drawable="@drawable/btn_big_popsubmit_disable" />
    <item android:state_enabled="true" android:state_pressed="true"
android:drawable="@drawable/btn_big_popsubmit_press" />
    <item android:state_enabled="false"
android:drawable="@drawable/btn_big_popsubmit_disable" />
    <item android:drawable="@drawable/btn_big_popsubmit_normal" />