Moving layout on the fly

Given the layout of main.xml below, is it possible to change the "layout_gravity" for FrameLayout at run time with immediate result?

My main layout is LinearLayout and a centered FrameLayout child with two children, SurfaceView and ImageView (located at the bottom of the frame).

I have a menu that allows the user to move the frame structure, which should be done by changing the layout_gravity to "top", "bottom" or "center".

For this, I use this code to change the gravity at runtime:

int mGravity = Gravity.TOP  // gravity determined from menu selection
FrameLayout mFrameLayout = (FrameLayout)findViewById(R.id.my_framelayout);
((LinearLayout.LayoutParams) mFrameLayout.getLayoutParams()).gravity = mGravity;

However, this does not work immediately. I just started working after the user clicks on another menu item that displays them on the Android Market. When a user returns from the market and returns to my application, only then a new layout is drawn in accordance with what the user previously selected.

Am I missing something simple? How can I force a redraw immediately after a user selects a position? What should I make invalid?

main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/ll_main"
android:layout_width="fill_parent"
android:layout_height="fill_parent">

<FrameLayout 
    android:id="@+id/my_framelayout"
    android:layout_width="fill_parent"
    android:layout_height="@dimen/surfaceview_default_h"
    android:layout_gravity="center">

    <SurfaceView 
        android:id="@+id/my_surfaceview" 
        android:layout_width="@dimen/surfaceview_default_w" 
        android:layout_height="@dimen/surfaceview_default_h">           
    </SurfaceView>

    <ImageView 
        android:id="@+id/my_imageview"
        android:layout_height="wrap_content" 
        android:layout_width="fill_parent"  
        android:src="@drawable/someimage" 
        android:layout_gravity="bottom">
    </ImageView>

</FrameLayout>
</LinearLayout>

menu.xml:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item 
    android:id="@+id/mnu_position"
    android:title="@string/position">
    <!-- Position submenu -->
    <menu>
        <group
            android:id="@+id/grp_position" 
            android:menuCategory="container" 
            android:checkableBehavior="single">
            <item 
                android:id="@+id/mnu_position_top" 
                android:title="@string/top">
            </item>
            <item 
                android:id="@+id/mnu_position_center"
                android:title="@string/center"
                android:checked="true"> 
            </item>
            <item
                android:id="@+id/mnu_position_bottom"
                android:title="@string/bottom">
            </item>
        </group>
    </menu>
</item>
<item 
    android:id="@+id/mnu_android_market" 
    android:title="@string/market">
</item>
</menu>