suggest you first try your own code against latest daily build, cuz it appears that…
from dawn of time to build 2992, problem existed cuz only integral coordinates reported
some time prior to 2994, fractional coordinates were added (but still quantized to content dimensions)
some time prior to 2999, fractional coordinates do NOT appear to be quantized any more
(that is, all possible fractional values appear to be being reported)
attached is what i was going to submit as a bug report myself, but am no longer planning to do so as I no longer see the problem myself. if you still see the problem, feel free to use/reuse it if it helps in any way as a bug submission of your own.