It is certainly possible to implement AutoFilterable using a new model type. On top of my head, I would consider creating a new AutoFilterableTableModel extending FilterableTableModel and add an extra row as the first row and use it as the fitler row. Never tried but it should work in my opinion.
For the nested table header, I also thought in that direction. I was thinking set a CellSpanTable to table header area. Then we get the spanning on the table header. But we lost column rearrange feature and will need some effort to do it.
That sounds pretty complicated to me. But why would you want to set a CellSpanTable for the nested header? Cant the existing NestedTableHeader be used?
We are currently making use of the nested table header feature but would like to use the auto filterable header feature as well. Both features would have to be part of the same table. Is there some time frame by when this can be expected?
The current NestedTableHeader cannot be easily extented. In comparison, the table features such as cell style, cell span etc, are very flexible and extensible. So we always wanted to align the both techniques to the same one. Well, I never said it is easy. We really just think about it and don't have any concrete plan for it at the moment.