I feel it would be nice/useful to have the option to disable delta frame (allowing full frame redraw). Delta Frame can cause issues with specific types of animations.
A case example would be a animation which uses transparency. It will need to overwrite pixels that are no longer used, but delta frames will crop out these pixels resulting in a broken animation, leaving the programmer with one of two types of images:

1. A animation with random cropping(Notice the feet/head): https://i.imgur.com/xnh6Lq5.gif
2. A animation with ghosting: https://i.imgur.com/uCekDte.gif

Example of a implementation:
GifImagePlugin.py.diff.txt (Had to save it as a .txt because for some reason Github doesn't allow diff of all file types to reject)
Attached diff is messy, could be optimized (doesn't disable cropping code), and the name probably could be less long.

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Edit: This might actually be a bug?
Turns out the issue only seems to occur if the background transparency data in a png contains color information and isn't empty/same color.