DataGrid Footers

Ever notice that the DataGrid has headers but no footers? That’s because footers have to be computed if they are totals or averages or whatever and we wanted to leave that for advanced datagrids in a future release.
Lately, due to some other work we’re doing for 3.0, I’ve been wondering whether footers, headers and locked columns and rows should be part of the chrome instead of the main set of cells. If so, it is possible to create footers in 2.0.1 today by subclassing DataGrid and making a special Border that can put renderers in the border.
Here’s an example that computes the average of the price column. Usual caveats apply.
Download source
Run demo
You can see how one could do column headers that way, or add headers to Tree for a TreeDataGrid.
Now, if the renderers are in the chrome, they are not part of the selection model, and they should probably not renderer data from the dataprovider per-se. So I’d be interested in knowing:
1) If you have used lockedColumns or lockedRows today, what have you used them for?
2) Did you want the lockedColumns or lockedRows to be selectable? Editable?
3) Did you do this to get more header rows/columns or to display data from the dataprovider?