1. click Zone Adjustment OK with Display Zones or Masks button pushed down
2. reopen the Zone Adjustment dialog -> the "Z" ("M") button stays pushed down but the preview shows the output image
3. to get back the corresponding preview you need to move one of the sliders a bit or switch the Z-M-A buttons or the tabs.
However, if you instead of the step 3 close the dialog using Cancel or X button, the thumbnail image and its preview do not switch to show the resulting output. They keep on showing the zones or masks respectively.
Zone Adjustment hitches
Moderator: jsachs