The problem exists only for acrobat and only under Windows. Nobody has complained about LyX's behaviour in this regard in 10 years of existence. That suggests that people like LyX's behaviour.
This problem also happens for acrobat reader under linux.
If you want to compare to previous versions, use the change tracking and version control features.
You can not easily preview a previous version-controlled version, and one do not check in often. Bo
