Hi,
I've noticed that when I merge 2 or more layers, a clear "outline" a few pixels wide is added to the newly created object/layer.
1. Using the lasso tool, I make a selection from one layer (original photo/background usually), and I paste the selection into a new, blank layer.
2. I repeat step one.
3. I merge the 2 new layers created in steps 1 & 2. The contents of this layer is no longer "clean" - it has a clear/empty border/outline of around 3 pixels or so added all around the merged art/object on this layer.
Not sure if this qualifies as a bug, but it's definitely a major pain, cause depending on how I use this new layer, I have to clean up the edges all over again.
I am using the latest version of Photo on the latest version of Mac OS.