P.S. @ taersh: As I run several Puppies I've created a pet to install the files discussed above rather than having to do it manually for each current and future Puppy. I'm currently on Bionicpup64 which employs Wine-portable rather than the Wine-Staging.AppImage. Not exactly certain what your post meant, I file-browsed to /etc/xdg/rox.sourceforge.net/MIME-types/ to examine what was there. It already contained a file named "application_x-ms-dos-executable". Opening it in geany revealed
#/bin/sh
exec wine.sh "$@"
which is the appropriate command for wine-portable and AFAIK was written when 'Registering' portable-wine.
[IIRC, on Fossapup64, where I did deploy the Wine-Staging.AppImage, when I went to run the first exe, I had to first right-click it and "set run command" as "wine "$@" --with "$@" already present].