Hi,
since the current persistency models do not work (at least for me), I
have created my own which saves the image on each modification:
PRPersistency suclass: #PRSaveImagePersistency
...
PRSaveImagePersistency>>snapshot
[SmalltalkImage current snapshot: true andQuit: false]
forkAt: Processor userBackgroundPriority
PRSaveImagePersistency>>log: aContext
self snapshot
PRSaveImagePersistency>>do: aBlock
Nothing more