How about saving images, sounds and music inside GDG file? I know that GDG is XML file, but (at least images) can be stored as text using base64 encoding. For example this image
would look in text form like this:
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I believe same goes for other binary formats, including sound formats like OGG or WAV.
This way we won’t worry forever if we copied all project files into new drive/backuped before format. We will only have to copy GDG file and we are set. This would also make “Save in portable version” option obsolete.