We're going to have GimpImageProxy implement GimpPickable, so that it can be used as either a viewable or a pickable proxy for an image. (cherry picked from commit 8d8cc12f40)
8d8cc12f40
... in preparation for actually renaming the class, but as a separate step to keep the history. (cherry picked from commit 0ddd3330b8)
0ddd3330b8
