XAML Vertically align only top stackpanel

Question

I have a view that contains two stackpanels (main ones). The top one is a spinner and "One Moment Please..." that I need centered vertically. The bottom one appears when the top one disappears and I need it stretched so the content appears at the top of the window.

     <ScrollViewer VerticalScrollBarVisibility="Auto">
            <StackPanel HorizontalAlignment="Stretch" VerticalAlignment="Center">
                <local:BusyIndicator VerticalAlignment="Center" HorizontalAlignment="Center" Width="50" Height="50" Visibility="{Binding Path=IsBusy, Converter={StaticResource booleanToVisibilityConverter}}"/>
                <TextBlock  VerticalAlignment="Center" HorizontalAlignment="Center" Text="One Moment Please" Visibility="{Binding Path=IsBusy, Converter={StaticResource booleanToVisibilityConverter}}"/>
                <StackPanel HorizontalAlignment="Center" Visibility="{Binding Path=HasError, Converter={StaticResource booleanToVisibilityConverter}}">
                    <TextBlock
                    Visibility="{Binding Path=HasError, Converter={StaticResource booleanToVisibilityConverter}}"
                    Text="{Binding Path=ErrorMessage}" VerticalAlignment="Center" HorizontalAlignment="Center" FontSize="12" TextWrapping="Wrap"/>
                </StackPanel>
                <StackPanel VerticalAlignment="Stretch" Orientation="Vertical" Visibility="{Binding Path=IsBusy, Converter={StaticResource inverseBooleanToVisibilityConverter}}">
</Stackpanel>
</ScrollViewer>

The issue that keeps happening is that the bottom stackpanel is vertically centered and the content does not move to the top of the window.

I apologize but I am not able to show the actual view (NDA). What I am trying to do (Right Image), what is happening (Left Image). NOTE: Only the text or the spinner show up at one time. I am not trying to align the two, just make the spinner center vertically when the text is not displayed.

Answer 1

Does your booleanToVisibilityConverter return Visibility.Collapsed or .Hidden for False? It should return Collapsed in order for the space to be reclaimed.