This is Luke from Korean partner, Goldpitcher. One of our customer requested to be get project category reiterated like this.

Team A (Category)
Linux (Category)
Project A
Project B
Project C
Windows(Category)
Project D
Project F
Project M

Team B (Category)
Linux (Category)
Project G
Project H
Project I
Windows(Category)
Project J
Project K
Project L

I think it seems like not simple function to implement but it is useful for some situations. Cheers.