If a project file is read-only, it is probably a sample project since
all sample project files have the read-only attribute set. This prevents
users from accidentally overwriting the project file. In order to be able
to save the (customized) project later, the application can copy the read-only
file to another, not read-only project file and then continue with the
copied version.
If you choose not copy the project file, you can still customize it
but in order to save it, you need to save it to another file or remove
the read-only attribute from the file first.