I remember using KDE Partition Manager in the past to resize fat32 partitions. Now it says in the "File System Support" that grow & shrink are not supported for fat32, fat16, or fat12.
I can't find any information on why this happened.
It appears that KDE Partition Manager does not depend on GNU parted. Did it depend on parted at the time when it supported resizing vfat partitions?

Yeah, that sucks. I now need to have GParted installed only to do this.