Drawer Like Feature WPF Grid - wpf

Question

I am stuck creating a UI...
I have created a Grid and it contains 3 Columns -
1st Column - A grid which contains all the inputs that i need from the user
2nd Column - A gridSplitter
3rd Column - Again a grid which contains all the outputs
I want to implement a button as in the RED Circle which on click Hides/Shows my 1st Column i.e. the input portion and hence the user can see the entire Output on the whole of the screen..
Here is my code this far -
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Top">
<Grid Grid.Row="0" RenderTransformOrigin="0.5,0.5" Margin="20,0,20,20">
<Grid.RowDefinitions>
<RowDefinition Height="124"/>
<RowDefinition Height="8*" />
<RowDefinition Height="5*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" MinWidth="1100" />
</Grid.ColumnDefinitions>
<Grid x:Name="InputGrid" Grid.Row="0" Grid.Column="0" />
<GridSplitter HorizontalAlignment="Right" VerticalAlignment="Stretch"
Grid.Column="1" ResizeBehavior="PreviousAndNext" Width="3" />
<Grid x:Name="OutputGrid" Grid.Row="0" Grid.Column="2"/>
</Grid>

Answer 1

I added a button to your xaml, just as an example:
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Top">
<Grid Grid.Row="0" RenderTransformOrigin="0.5,0.5" Margin="20,0,20,20">
<Grid.RowDefinitions>
<RowDefinition Height="124"/>
<RowDefinition Height="8*" />
<RowDefinition Height="5*" />
<RowDefinition Height="Auto" /><!--for the button (just an example)-->
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" MinWidth="1100" />
</Grid.ColumnDefinitions>
<Grid x:Name="InputGrid" Grid.Row="0" Grid.Column="0" Width="250" Background="Blue"/>
<GridSplitter HorizontalAlignment="Right" VerticalAlignment="Stretch" Grid.Column="1" ResizeBehavior="PreviousAndNext" Width="3" />
<Grid x:Name="OutputGrid" Grid.Row="0" Grid.Column="2" Background="Yellow"/>
<Button Grid.Row="4" Content="test" Click="OnButtonClick"/>
</Grid>
</Grid>
in code behind toggle visibility of the grid:
private void OnButtonClick(object sender, RoutedEventArgs e)
{
InputGrid.Visibility = InputGrid.Visibility == Visibility.Visible
? Visibility.Collapsed
: Visibility.Visible;
}