In the add comment dialoge there is an option to add a time/date to the
image comments.  There is an option to add the time from the file creation
date.  Apparently it is getting this information from the file's ctime,
which is not all that useful because it merely contains when the inode was
allocated on that filesystem.

The ctime is not modifiable by any system call.  The only way to change it
is to hack the filesystem itself.  It would probably be much more useful
for this feature to take the mtime of the file.  For example, if I transfer
files from my digital camera to my hard drive that I took 2 months ago,
then use this feature, taking the ctime will add the time that they were
transferred to the hard drive rather than the date the camera placed on the
files.

Using the mtime is probably what most users want since that would contain
the time the picture was actually created, assuming that the date was set
correctly on the digital camera of course.