picolanginstaller/res/layout/installing.xml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/root" android:layout_width="fill_parent"
    android:background="#ff000000"
    android:layout_height="fill_parent">
    
     <LinearLayout android:id="@+id/progress_indicator"
        android:orientation="vertical"
        android:layout_centerInParent="true"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        
        <TextView android:paddingTop="5dip"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/installing_message" android:textSize="18sp"
            android:textColor="?android:attr/textColorPrimary" />
            
        <ProgressBar android:id="@android:id/progress"
            style="?android:attr/progressBarStyleLarge"
            android:layout_gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />            
    </LinearLayout>

</RelativeLayout>