Trouble opening plist files in text editor
plist files are not necessarily plain text so they need to be run through a converter. Finder and Xcode (which has a plist editor) do this without telling the user

The binary format is documented in this C code so any application can convert it and someone has written a format description in English and more Apple documentation here but note that it references old paths in /Developer/Documentation

The command line program plutil can convert to and from XML

e.g. to view a binary property list in XML format on stdout:

plutil -convert xml1 -o - &lt;file name&gt;


Also to convert a binary to a XML plist in place and then leave it so that the user program can read either.

plutil -convert xml1 &lt;file name&gt;