At first I though it was probably my old 2012 MacPro limping along, but I also confirmed it with a neighbor using a newer Windows 10 machine...
When I'm using the Healing Brush, the little black marks it makes to indicate the area being healed remain on the screen for a minute or more unless I manually refresh the display by quickly magnifying the image and then reducing it. They disappear with the refresh. I have no reason to believe the healing isn't taking place in a timely fashion, just the display problem.
Also, when using a selection tool, the selection causes a larger, rectangular "pane" of the image to pop up and shift for a moment before coming back to rest properly. Makes it almost impossible to make multiple rapid selections.
2012 6 core MacPro 5,1 32 GB RAM Mac OS 10.13.6
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