This is not true. You need to change the file format, because if people open such a file with an older version that doesn't have this checkbox, LyX will crash.
Let us just forget about RC1, which is meant to be experimental. 1.5.0 ==> 1.4.x Current lyx2lyx translate listings to ERT. No problem. 1.5.0 ==> > 1.5.x No file format problem.
1.5.x ==> 1.5.0
Parameters are *not* validated so the file can be compiled as long as a user is using a capable listings package. If some parameter is acceptable by 1.5.2, but not 1.5.0, a user will be in trouble only when he use GUI to edit the inset. In this case, he can use this bypass button. Because RC1 does not acceptable unrecognized parameters, RC1 1. ignore all global parameters (try/catch in bufferparam.cpp) if a global parameter is not recognized. 2. may crash or compile for normal insets (need to check code). 3. GUI will not work for unrecognized parameter. The only solution would be using ERT from 1.5.x => RC1. Cheers, Bo
