Just to add to what NJDude said, you need to add "|adjustPan" to whatever is in android:windowSoftInputMode.
Normally the activity node we're interested in will look like this:
<activity android:windowSoftInputMode="stateHidden" android:launchMode="singleTop" android:name="mainmenu" android:label="mainMenu" android:screenOrientation="portrait"></activity>
you want to make it look like this:
<activity android:windowSoftInputMode="stateHidden|adjustPan" android:launchMode="singleTop" android:name="mainmenu" android:label="mainMenu" android:screenOrientation="portrait"></activity>
You have to select "Do not overwrite manifest file" as well to ensure your changes are kept.