[Sony Cross-Device Development Themes and Apps] Ticklefish:
Good to see that things have gotten more complicated again...:rolleyes:

The layout of your portrait navbar is in "navigation_layout.xml":

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout android:layout_width="fill_parent" android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android" xmlns:systemui="http://schemas.android.com/apk/res-auto">
<FrameLayout android:id="@id/nav_buttons" android:layout_width="fill_parent" android:layout_height="fill_parent">
<LinearLayout android:orientation="horizontal" android:id="@id/ends_group" android:clipChildren="false" android:layout_width="fill_parent" android:layout_height="fill_parent" />
<LinearLayout android:gravity="center" android:orientation="horizontal" android:id="@id/center_group" android:clipChildren="false" android:layout_width="fill_parent" android:layout_height="fill_parent" />
</FrameLayout>
<com.android.systemui.statusbar.policy.DeadZone android:layout_gravity="top" android:id="@id/deadzone" android:layout_width="fill_parent" android:layout_height="fill_parent" systemui:minSize="@dimen/navigation_bar_deadzone_size" systemui:maxSize="@dimen/navigation_bar_deadzone_size_max" systemui:holdTime="@integer/navigation_bar_deadzone_hold" systemui:decayTime="@integer/navigation_bar_deadzone_decay" systemui:orientation="horizontal" />
</FrameLayout>

Personally I'd be tempted to try to track down those "@id/ends_group[/b"] and "@id/center_group" references and see if there are XML files that connect to those which have the icons in.

However, for now, we can do some experimenting.

You could try putting the HorizontalScrollView in this file:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout android:layout_width="fill_parent" android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android" xmlns:systemui="http://schemas.android.com/apk/res-auto">
<HorizontalScrollView android:scrollbars="none" android:layout_width="fill_parent" android:layout_height="wrap_content">
<LinearLayout android:orientation="horizontal" android:layout_width="wrap_content" android:layout_height="wrap_content">
<FrameLayout android:id="@id/nav_buttons" android:layout_width="fill_parent" android:layout_height="fill_parent">
<LinearLayout android:orientation="horizontal" android:id="@id/ends_group" android:clipChildren="false" android:layout_width="fill_parent" android:layout_height="fill_parent" />
<LinearLayout android:gravity="center" android:orientation="horizontal" android:id="@id/center_group" android:clipChildren="false" android:layout_width="fill_parent" android:layout_height="fill_parent" />
</FrameLayout>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@id/ModBackTrack" android:layout_width="@dimen/navigation_key_width" android:layout_height="fill_parent" android:src="@drawable/backwhite" android:scaleType="center" android:layout_weight="0.0" android:layout_marginEnd="@dimen/navigation_key_outer_margin" systemui:keyCode="88" />
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@id/ModPlayPause" android:layout_width="@dimen/navigation_key_width" android:layout_height="fill_parent" android:src="@drawable/playwhite" android:scaleType="center" android:layout_weight="0.0" android:layout_marginEnd="@dimen/navigation_key_outer_margin" systemui:keyCode="85" />
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@id/ModForwardTrack" android:layout_width="@dimen/navigation_key_width" android:layout_height="fill_parent" android:src="@drawable/forwardwhite" android:scaleType="center" android:layout_weight="0.0" android:layout_marginEnd="@dimen/navigation_key_outer_margin" systemui:keyCode="87" />
</LinearLayout>
</HorizontalScrollView>
<com.android.systemui.statusbar.policy.DeadZone android:layout_gravity="top" android:id="@id/deadzone" android:layout_width="fill_parent" android:layout_height="fill_parent" systemui:minSize="@dimen/navigation_bar_deadzone_size" systemui:maxSize="@dimen/navigation_bar_deadzone_size_max" systemui:holdTime="@integer/navigation_bar_deadzone_hold" systemui:decayTime="@integer/navigation_bar_deadzone_decay" systemui:orientation="horizontal" />
</FrameLayout>

I can't guarantee this will work so make sure you make a backup first!