Every now and then the question arises why we don’t have a button in darktable to open the current image in GIMP. Everytime I answer more or less the same.
The arguments of those requesting the button are along the line of “$PROGRAM has it, so it shouldn’t be hard to do” and “I really need to do some small retouching, so it would save me lots of time”.
Well, to understand why we don’t have it I have to stress two features of darktable. First of all, every action is done non-destructive. What that means is that you never edit the actual data in your raw file, but “record” a list of actions (the history in darkroom mode and the XMP files) which shall be executed to get the final image. This list can be changed afterwards without negative side effects since those actions can just be recomputed. The second nice thing in darktable is that we work with high bit depths (32 bit floating point) to get the best possible result.
This is a companion discussion topic for the original entry at https://www.darktable.org/2011/03/why-gimp-doesnt-play-well-with-darktable/