Can I nest a PopupLayout (or RelativeLayout) inside another layout?

I am trying to place a Map control inside of a PopupLayout, where the PopupLayout doesn't start at the top of the screen.
I have something like this:

<StackLayout>
     <xform:AutoCompleteView.../>
     <xform:PopupLayout>
        <xform:PopupLayout.Content>
            <maps:map/>
         </xform:PopupLayout.Content>
      </xform:PopupLayout>
</StackLayout>

The problem is that the map doesn't fill the popuplayout. It leaves a blank gap, and starts roughly the size of AutoCompleteView. Lets say AutoCompleteView is 50 px high, then the map is starting at 100 px.
This doesn't happen if I use a stacklayout instead of a popuplayout.
Is the issue that PopupLayout expects to be the first layout, and can't be nested inside another layout?