I'm creating a form, that will display to controls side-by-side, like example bellow.
The problem is that when I set visibility of one control to "Collapsed", the other one does not fill all window.

```
<Window x:Class="Example"
        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" 
        WindowStartupLocation="CenterScreen"
        Height="600" Width="600">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Button>Button 1</Button>
        <Button Grid.Column="1" Visibility="Visible">Button 2</Button>
    </Grid>
</Window>

```

How can I make "Button 1" to fill all window, when I set button2 visibility to collapsed?

Current effect when both visible:

```
+---------------------+
|          |          |  
|          |          |  
|          |          |  
| Button 1 | Button 2 |  
|          |          |  
|          |          |  
|          |          |  
+---------------------+

```

When Button2 is collapsed:

```
+---------------------+
|          |          |  
|          |          |  
|          |          |  
| Button 1 |          |  
|          |          |  
|          |          |  
|          |          |  
+---------------------+

```

Desired:

```
+---------------------+
|                     |  
|                     |  
|                     |  
|      Button 1       |  
|                     |  
|                     |  
|                     |  
+---------------------+

```