FrameLayout not respecting draw order

Question

I've this layout hierarchy:

<FrameLayout>

    <ScrollView>...</ScrollView>

    <LinearLayout>...</LinearLayout>

    <LinearLayout>...</LinearLayout>

</FrameLayout> 

Using the Android Device Monitor I've dumped the view hierarchy and I've achieved this:

As expected. But if I include two more layouts:

<FrameLayout>

    <ScrollView>...</ScrollView>

    <LinearLayout>...</LinearLayout>

    <LinearLayout>...</LinearLayout>

    <include layout="@layout/a_framelayout"/>

    <include layout="@layout/another_framelayout"/>

</FrameLayout> 

Note: a_framelayout contains a LinearLayout and another_framelayout contains a View.

I get this:

Shouldn't this two layouts have a index of 3 and 4 respectively instead of 0 and 2? And why is the ScrollView between them?

If I change the layout to:

<FrameLayout>

    <include layout="@layout/a_framelayout"/>

    <include layout="@layout/another_framelayout"/>

    <ScrollView>...</ScrollView>

    <LinearLayout>...</LinearLayout>

    <LinearLayout>...</LinearLayout>

</FrameLayout> 

I get:

It makes more sense, but now the a_framelayout was swapped with another_framelayout, why?

Although this strange layout behaviour happened, all views were correctly rendered in the screen and the layout works as it should.

Any clue?
Thanks for your time.