Stupid DataGridViews do not commit data to datasource when asked

I'm hoping I'm missing something really obvious here. The scenario is this :

1. You have a data grid view linked to a binding source linked to a dataset.
2. If you add a new row, move to another row, and then delete the row you added, all is good.
3. If you add a new row, save it (using dgv.CommitEdits), when you delete it you will get an error along the lines of the index does not exist.

This stumped me for quite a while. Turns out you must call the BindingSource.EndEdit. The dgv CommitEdits only stores them as far as the binding source. dgv.EndEdit only commits the current cell. As far as I can see there are no methods in the dgv to do this pass through. Even more annoying, you delete the row from the dataset, not from the binding source or from the grid.

It's little things like this that take far too long to work out.