Wpf application with a fixed panel - wpf

Question

I need to create a Wpf application with this type of navigation:
A main screen with a fixed top panel, and the rest of the window that acts as a container for other views. The container can be populated with 0 or 1 views - there's never a situation when 2 or more windows should be seen at the time in this container.
I've added this very childish drawing I made:
The top green panel is the navigation panel, and when pressing "A" button, I need viewA to be opened in the red part of the window.
Similarly, when pressing "B" button, I need viewB to be opened in the red part of the window instead of viewA.
My questions:
What objects should I use to represent viewA, viewB and the containing window? Are these Windows? Pages?
What is the best way of switching between viewA and viewB? I prefer avoiding loading both viewA and viewB (and any other view I'll have) into memory and just hide\show them..
Thanks.

Answer 1

You could put all the "Green" stuff in directly in your window and "Red" stuff (UserControl likely) inside a ContentControl and then bind the Content property of that to the red's stuff. So it'd be like this:
<Window x:Class="garbage.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition Height="3*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<!--Green stuff-->
<Button Content="A" />
<Button Content="B" Grid.Column="1"/>
<ContentControl Grid.Row="1" Grid.ColumnSpan="2" Content="{Binding RedStuff}">
</ContentControl>
</Grid>