Build a parameter and calculated field:
IF [Category]=[Category Parameter]
Then put it to Detail, click Color, sorting by max(top sorting), desc.
Done. See workbook in V10.2
Hope it helps.
sorting.twbx 1.2 MB
The top sort idea really sorted my problem .
Any ideas how to reverse this through a formula.
If you want to reverse, which means put it in the bottom when selected, just using ascending instead of descending.