title: wpf - Grid column not filling remaining space when other column's contents are collapsed
body: <p>I've got a grid with 3 columns: the first has its Width set to "*", which I have been led to believe will make it fill up any remaining space left by the other columns. The second has a width of 8, and the third's Width is set to "Auto" so its size changes depending on its contents.</p>
  
  <p>In my 2nd column I have a <code>GridSplitter</code>, so that when dragged I can change the width of both the first and third columns. This works fine, the issue is that I have a grid in my third column that, when toggled, will have its visibility set to collapsed. When collapsed, I need the first column to fill all of the remaining space. I tried to do this many ways:</p>
  
  <ul>
  <li>Set <code>HorizontalAlignment</code> on first column to <code>Stretch</code></li>
  <li>Bound the <code>Grid.Rowspan</code> of the first column to the visibility of the third one, so that when when hidden the Rowspan will change to 3 and, since its width is using "*", it should theoretically use all of the available space in all 3 columns.</li>
  </ul>
  
  <p>The weird thing is that, if I do not resize the columns using the <code>GridSplitter</code>, then the first column will fill all remaining space properly. Yet after resizing, the first column will not budge. It's almost as if, when dragging the GridSplitter to resize the columns, WPF change the width of both columns to become absolute instead of their star and auto values, making it so they will not fill the space after a resize.</p>
  
  <p>XAML Code (condensed) as requested:</p>
  
  <pre><code>&lt;Grid Grid.Row="1"&gt;
              &lt;Grid.ColumnDefinitions&gt;
                  &lt;ColumnDefinition Width="*"/&gt;
                  &lt;ColumnDefinition Width="Auto"/&gt;
                  &lt;ColumnDefinition Width="Auto"/&gt;
              &lt;/Grid.ColumnDefinitions&gt;
      &lt;Grid x:Name="AssetListViewGrid" Grid.Column="0" Grid.RowSpan="{Binding Visibility, ElementName=AssetViewMetadataSplitter, Converter={StaticResource SplitterVisibilityToRowSpanConverter}}"  Margin="0 4 0 4"&gt;
      &lt;!-- irrelevant code --&gt;
      &lt;/Grid&gt;
  &lt;GridSplitter x:Name="AssetViewMetadataSplitter" Grid.Column="1" Opacity="0.8" HorizontalAlignment="Center" Width="6" Margin="3 5 1 5" ToolTip="Grab to resize" Visibility="{Binding IsChecked, ElementName=GridHeaderVisibilityToggleButton, Converter={StaticResource VisConverter}}"/&gt;
  &lt;Grid x:Name="MetadataGrid" Margin="4 2 4 2" Grid.Column="2" DataContext="{Binding MetadataViewModel}" Visibility="{Binding IsChecked, ElementName=GridHeaderVisibilityToggleButton, Converter={StaticResource VisConverter}}"&gt;
      &lt;!-- irrelevant code --&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p></p>