Cross tables in Windows Forms - data binding magic

I have this sample from a recent talk at Basta! conference in Germany, which shows (among other things) how to bind a cross table to a DataGridView (the standard .NET 2 data grid). A cross table is basically the result of transposing some data and using one of the fields for a second dimension.

The sample I have works on two tables of data. It doesn't actually use a database and the reference that points from the list of votes to that of features is implemented as an object reference, but the relationship is like this:

Now, let's assume there's this data in the two tables/lists:

Features
ID	*Name*
1	Synthesize out-of-the-box supply-chains
2	Syndicate vertical mindshare

Votes
ID	*Feature_ID*	*Year*	*Priority*
1	1	2004	30
2	1	2005	40
3	1	2006	70
4	2	2004	70
5	2	2005	60
6	2	2006	30

In a cross table the same data could look like this:

Feature/Year	2004	2005	2006
Synthesize out-of-the-box supply-chains	30	40	70
Syndicate vertical mindshare	70	60	30

This is exactly the kind of transformation demonstrated in my sample. Now, there are a number of other things in that program, so don't be confused. I suggest you focus on the workings of the VoteValuePropertyDescriptor class.

Here's the download: FeatureVoting.zip