It's worth consideration to add filter control into PivotFieldControl macro. However, it may also take some discussions to establish the right spec to implement this.

1. The spec defined in Excel can be improved: field filter should be certainly independent from field type.
2. It requires much more information from the (extended) model, including field's value type, or accessing raw data of a field, which increase the complexity of model implementation.
3. It takes much more information to specify the UI, hence requiring more labels, more switches.
4. The best place to handle filtering is at the input data, but PivotFieldControl can only see the model. We either have to make the model concept dirtier or to make PivotFieldControl intercept raw data.