注册一个PopupWindow 显示出来按返回键居然不消失，很是郁闷，结果查查资料原来是没有设置background

加上一句

PopupWindow.setBackgroundDrawable(new BitmapDrawable());

就Ok了。

<!-- Sets the text styles -->
<?xml version="1.0" encoding="utf-8"?>
<!-- Sets the text styles -->
<resources>
     <style name="CustomWindowTitleText" parent="android:TextAppearance.WindowTitle">
          <item name="android:textSize">20dip</item>
          <item name="android:textColor">#5599FF</item>
          <item name="android:textStyle">bold|italic</item>
     </style>
     <!-- Changes the background color of the title bar -->
     <style name="CustomWindowTitleBackground">
           <item name="android:background">#222222</item>
     </style>

     <!-- Set the theme for the window title -->
     <!-- NOTE: setting android:textAppearence to style defined above -->
     <style name="CustomWindowTitle" parent="android:WindowTitle">
          <item name="android:textAppearance">@style/CustomWindowTitleText</item>
          <item name="android:shadowDx">0</item>
          <item name="android:shadowDy">0</item>
          <item name="android:shadowRadius">5</item>
          <item name="android:shadowColor">#1155CC</item>
      </style>
      <!-- Override properties in the default theme -->
      <!-- NOTE: you must explicitly the windowTitleSize property, the title bar will not re-size automatically, text will be clipped -->
      <style name="CustomTheme" parent="android:Theme">
           <item name="android:windowTitleSize">40dip</item>
           <item name="android:windowTitleStyle">@style/CustomWindowTitle</item>
           <item name="android:windowTitleBackgroundStyle">@style/CustomWindowTitleBackground</item>
      </style>
</resources>

<application android:icon="@drawable/icon" android:label="@string/app_name" android:theme="@style/CustomTheme">

 public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo)
   {    
        AdapterContextMenuInfo info = (AdapterContextMenuInfo) menuInfo;
        int position = info.position;

}