Bug 461553

currently, due to the bad performance issues with the liquify transform, i have to duplicate a single liquify transform mask; my workflow consists of applying a transform to a group with different versions of the same drawing.
my issue is, when turning invisible and visible again a layer with a liquify transform mask in it, krita recalculates the transform for no reason! however, krita knows to not do this if i wrap the layer in an additional group.

STEPS TO REPRODUCE:
1. create a layer with content on it
2. add a liquify transform mask to it
3. toggle visibility of the paint layer; the layer should take several seconds to recalculate the transform (for big enough layers), even though there was nothing to recalculate
4. put the layer in a group and toggle the visibility of the group; suddenly krita knows to not recalculate the transform, and there is no delay in rendering the layer.

p.s it would have been great if i could have avoided this mask duplication altogether, and just have krita properly cache the transform for every layer in the group for a fast preview, or, ideally, for the liquify performance issues to be amended.