How to resize controls at runtime in WPF

Question

There is DockPanel with three child controls placed side by side in a horizontal manner: 1) TreeView 2) RichTextBox 3) Grid

RichTextBox lies in middle of TreeView and Grid. I made RichTextBox the last child of DockPanel and set LastChildFill attribute to True. Now since Grid can be closed at run time, I want the RichTextBox to occupy all the space that became empty after the Grid is closed. But if the Grid is again shown the RichTextBox should contract from Right hand side to allow the Grid to fit in. How to achieve this? I'm new to WPF. Also, how to hide the Grid? Here is the XAML.

    <DockPanel Grid.Row="2" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" LastChildFill="True">
        <Border BorderThickness="1" DockPanel.Dock="Left" Height="Auto" HorizontalAlignment="Stretch" Margin="1" VerticalAlignment="Stretch" Width="Auto" CornerRadius="0" BorderBrush="#FF646464">
            <TreeView Name="TV" Height="Auto" Width="Auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
        </Border>
        <Border Name="Notification_Pane"  BorderThickness="1" DockPanel.Dock="Right" Height="Auto" HorizontalAlignment="Stretch" Margin="1" VerticalAlignment="Stretch" Width="Auto" CornerRadius="0" BorderBrush="#FF646464">
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto" />
                    <RowDefinition Height="*" />
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*" />
                    <ColumnDefinition Width="Auto" />
                </Grid.ColumnDefinitions>
                <Label Content="Notification" Margin="0" HorizontalAlignment="Stretch" VerticalAlignment="Top" Background="LemonChiffon" Grid.Row="0" Grid.Column="0"/>
                <Button Name="btn_Close" Content="X" Margin="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Background="LemonChiffon" Height="Auto" Width="Auto" Grid.Row="0" Grid.Column="1" Padding="10,0,10,0" BorderThickness="0" Cursor="Hand" Focusable="True" IsHitTestVisible="True" ClickMode="Release" Click="Button_Click" />
                <ScrollViewer Height="Auto" Name="ScrollViewer" Width="Auto" Margin="0" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2">
                    <StackPanel CanVerticallyScroll="True" Height="Auto" Name="Notification_Panel" Width="Auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">

                    </StackPanel>
                </ScrollViewer>
            </Grid>
        </Border>
        <Border BorderThickness="1" Height="Auto" HorizontalAlignment="Stretch" Margin="1" VerticalAlignment="Stretch" Width="Auto" CornerRadius="0" BorderBrush="#FF646464">
            <RichTextBox Name="rtb" Height="Auto" Width="Auto" Grid.Row="2" HorizontalAlignment="Stretch" Grid.Column="1" Margin="0" />
        </Border>
    </DockPanel>

Answer 1

You can use Grid.Visibility property to show and hide the grid. The following code should do the job:

    private void Button_Click(object sender, RoutedEventArgs e) //X Button click event.
    {
        //grid is the name of our Grid Control we want to hide.
        grid.Visibility = System.Windows.Visibility.Collapsed;
    }

to show the grid again you should use the following code:

grid.Visibility = System.Windows.Visibility.Visible;

The RichTextBox control will always fit in the DockPanel Control.