Problem Statement:
Showing multiple overlays in single view using WPF Prism region manager and regions
Solution:
Have region using ItemsControl or Listbox
Listbox XAML Sample
ItemsControl XAML Sample
Bind your regions with multiple views to show as overlay
regionManager.Regions[MultipleOverlayRegion].Add(overlayView1);
regionManager.Regions[MultipleOverlayRegion].Add(overlayView2);
Showing multiple overlays in single view using WPF Prism region manager and regions
Solution:
Have region using ItemsControl or Listbox
Listbox XAML Sample
<ListBox x:Name=" MultipleOverlayRegion "
PrismRegions:RegionManager.RegionName="MultipleOverlayRegion">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<Grid></Grid>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<Grid>
<ContentControl Content="{Binding}" />
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem"
BasedOn="{StaticResource {x:Type ListBoxItem}}">
<Setter Property="VerticalContentAlignment"
Value="Stretch" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<ContentPresenter />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ListBox.ItemContainerStyle>
</ListBox>
<ItemsControl x:Name="MultipleOverLayRegion">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Grid></Grid>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
regionManager.Regions[MultipleOverlayRegion].Add(overlayView1);
regionManager.Regions[MultipleOverlayRegion].Add(overlayView2);