Well, this would be trivial to make backwards compatible were the necessary imager fix only PasteUpMorph disableDeferredUpdates: true. Here's how. 1. introduce a new flag bit in the image flags (alongside full screen, preemption yields, send wheel events, do mixed arithmetic, et al). This bit is unset in old images 2. have the beDIsplay primitive #102 interrogate this bit and if unset invoke primitiveDeferDisplayUpdates's innards with false as the effective argument 3. set the flag bit in new images
Now if there's a way of side effecting the canvas in old images we have a solution, no?