No, this is a bug. I fixed it in the development version (a beta is going to be out in about 1 or 2 weeks).
In the meanwhile you can use this workaround:
Change bitwidth from 32 to something else and the change it back to 32, then you can enter also values up to FFFFFFFF.
Okay, you can download it from here http://mh-nexus.de/hxd
I'll update the website later to add the change log, but the change log is also available in the ZIP-file.