Here is a patch to provide an explicit message that the file will be
converted when the file is opened (also querying what encoding should be
converted from), answering the complaint that the conversion is without
notice.

If you want to edit Python 2.x scripts with IDLE 3, you need to add
encoding declarations to the files. For bigger projects, it is
reasonable to expect that they do add these declarations.

Again, please only report one issue at the time. You chose to make
Python source files the topic of this issue, so please don't divert into
config or text files.