问Android活动边框不能移除吗？

EN

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    
    android:id="@+id/mainParent"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/bgdark"
    android:orientation="vertical" 
>
    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="match_parent"
        android:layout_height="76dp"
        android:src="@drawable/myheader_250x60" 
    />
    <ListView
        android:id="@+id/mainListview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </ListView>
</LinearLayout>