A solution to loss of data!
when modifying a new internal or an external image, for example when texture painting, all modifications to the image are lost if blender crashes or the user forgets to manually save the image independently of the blend file (clicking save in the blender file menu doesn't save modifications to images).
I think a good solution would be for all modified image datablocks to be backed up to a new internal location 'packed_backups'. This would happen whenever blender auto saves, or when the user manually saves the blend file.
This would not affect external image files, or original packed images.
When blender restarts or loads a blend file, any image datablocks that have an entry in 'packed_backups' would update to use the data from packed_backups rather than the original packed data or the original external image file data.
The user can click alt R at any time to reload the original versions and discard the 'packed_backups' version.
2 Comments
I know this doesn't answer to all of your concerns for accidental crash, but here is a way to intentionally cut out the middle man when saving the file as well as saving/packing the images. The caveat is that this is eliminating the ability to go backward in your painting back to steps prior, so committing to status is required. Short cut is Ctrl-Shift-S and the menu item is in the File>Save dropdown. github.com/artistCDMJ/Save_Plus
"(clicking save in the blender file menu doesn't save modifications to images)"
But it COULD be if someone were to combine pack all images as an operator with the same operator for save file in one button - but users will say that didn't want that much data in their file, or that they didn't intend on losing their history with the painting.
I will see if I can make a simple enough script to add a new save with images button in the file header. It won't be official though, I'm not there yet.