Combine expander and grid (resizable expander)

Question

I would like to have something like a resizable Expander. My basic idea was something like this:

Answer 1

Maybe this will help to solve your "column collapse" problem

XAML:

Add in Name="expGrid" and add in Collapsed="Expander_Collapsed"

C# Code:

private void Expander_Collapsed(object sender, RoutedEventArgs e)
{
  var colomnIndex = Grid.GetColumn(sender as Expander);
  var colomn = expGrid.ColumnDefinitions[colomnIndex];
  colomn.Width = GridLength.Auto;
}