Dune, thanks for the heads up on PNG's. I didn't notice how big they were until you pointed it out.
I know how to use the Painted Shader in the 3D Main Preview using the button right above it, but I still don't understand why there is an identical button to start a Painted Shader session in the Top Down, kind of 2D view (whats the official name of that view?). I just don't know the terminology for that little/tiny preview where you can see your shading result as you click on different node layers to the left of that view. I usually right-click and select "Open in new Window" to get a bigger view to see the preview, and move my camera around.
*** I'm just wondering in what case(s) would you start a Painted Shader session in that window (2D/Top Down Preview) rather than directly in the main 3D Preview window (RTP Window). ***
The reason I ask is because I tried to paint a mask, like an Alpha Channel mask on a Painted Shader node, which was connected to my heightfield to mask it's edges to create a soft blend, but it didn't work as expected. I had to paint directly on my heightfield in the 3D view while in a Painted Shader session initiated from the 3D View, which seems weird to me. Maybe my mind is just not thinking properly about how this works, but I intuitively look at the Painted Shader node as a Grayscale Mask/Alpha Channel Image (like a 4th channel for Transparency in a TGA file for example). Are my paint strokes being stored in the Painted Shader, or on the Heightfield?
If none of this makes sense, if you/someone can just answer my main question in between the "***" I will be happy.