Has anybody actually used plslabelfunc in a Fortran program? I've been trying and it appears to be ignored. The demo program that follows (at least for me) gives no indication that 'label_fmt' ever gets called. So I thought I'd just check in case I'm doing something silly before I report a bug.
I'm using plplot 5.9.9 on Manjaro Linux (Arch derivative) with gfortran 4.7.2.