Starting the application. Selecting maps to convert. Conversion works too, but see caveat in comments.
What does not
Ctrl+A does not work in the «Open file» dialog, you have to select using Shift+click on first and last item if you want to select all maps in a directory
What was not tested
Everything was tested
CAVEAT: .ozfx3 files you wish to convert MUST be writeable for user who does the conversion. Program opens them «for writing», even though it does not actually modify the files, the conversion merely create new .png files aside to originals. If you copied them from CD/DVD and they still have 0444 permissions, you have to chmod them (chmod o+w *.ozfx3), otherwise the program will crash. Note that this is bug in program, not bug in wine. When explicitly denied write rights on .ozfx3 files in Windows, the result is same (crash)