If you use Unwrapping, and adjust the island position/scale for an object with displacement, you have no way of seeing the displaced result as you adjust. You can get to see the texture on the surface (once you’ve picked it from UV Edior > Use Texture - the Textures palette here of course is so crucial), and it’ll respect any tiling you do which is good. Although there’s the age old problem of displacement kicking in way too many times (I’ve pointed this out before on a completely unrelated tool). Seems odd for it to be doing the work behind the scenes as you adjust, but to not get a preview as you’re waiting for the application. Since it’s doing the work of displacing, maybe objects with displacement ticked get an option in UV Editor of Use Displacement?
Maybe it’s fine as it is though. Workaround of course is turn off displacement and then do the UV editing with the Use Texture option.
Unrelated, why would the UV Editor constrain itself to a non square aspect ratio, for an image like below? I dug a little bit and the texture used in the editor preview was determining the aspect ratio. But not in an expected way…
