First of all it's my first day using Xaml so this question might be dummy for you, but i totally got lost.

Overview

My technique is that i have MainWindow.xaml and it's split into three areas (using grid columns) the columns width being set automatically.

Based on some actions in the right column, the middle column with show a page let's say Page.xaml that exists in different namespace.

What i'm seeking for

The problem is i need to set the width and height for this page to be equal the middle column width and height as it will fit this area.

Notes

I have very small experience with xaml and binding techniques.

MainWindow.Xaml

<Window 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" 
    WindowState="Maximized"
    ResizeMode="NoResize"
    WindowStartupLocation="CenterScreen"
    Title="MainWindow" d:DesignWidth="1366" d:DesignHeight="768">

<Grid x:Name="MainGrid">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="1.2*" x:Name="LeftColoumn" />
        <ColumnDefinition Width="3*" x:Name="CenterColoumn" />
        <ColumnDefinition Width=".8*" x:Name="RightColoumn" />
    </Grid.ColumnDefinitions>

    <ScrollViewer Grid.Column="2">
        <StackPanel Orientation="Vertical" x:Name="RightStackPanel" Background="LightGray" >
            <Border BorderBrush="{x:Null}" Height="50" >
                <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" TextWrapping="Wrap" FontWeight="SemiBold" FontStyle="Normal" Margin="3" FontSize="20" >Others</TextBlock>
            </Border>
            <Expander x:Name="Expander1" Header="Others" Margin="0,0,10,0">
                <Button  Margin="0,0,0,0"  Width="{Binding ActualWidth, ElementName=RightStackPanel}" Background="White" Content="Add" Height="50" Click="Button_Click" ></Button>
            </Expander>

        </StackPanel>
    </ScrollViewer>

    <Frame  Grid.Column="0" x:Name="LeftFrame" Background="LightGray"  ></Frame>
    <Frame  Grid.Column="1" x:Name="CenterFrame" Background="DarkGray" ></Frame>

</Grid></Window>

Other Xaml file

<Page
  x:Name="Page"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
  xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
  mc:Ignorable="d"
  Title="Any" d:DesignWidth="1364" d:DesignHeight="868"
  >

<Grid>
    <Frame   Background="DarkGray" />

</Grid></Page>

MainWindow.xaml.cs

private void Button_Click(object sender, RoutedEventArgs e)
    {
        Frame middleFrame=CenterColumn;
        Otherxaml other=new Otherxaml();
        middleFrame.Source = new Uri("OtherxamlPage.xaml", UriKind.RelativeOrAbsolute);
    }