UPDATE: At least add separate TG's for expenses and income. User selectable TG account parents would be preferable, of course. I would sure like a retirement account/s TG, for example.
Also, please add a TG total and period average amount - to the right of the period selection would be a good place. I would also not miss the item totals below the TG bar. Those values take a large amount of page space and are easily seen via mouse-over the TG bar/s.