The mask problem I mentioned above is as follows: When I select the background pixel layer, and then the black mask and Paintbrush tool, the photo will erase as you pass over it with the Paintbrush tool. A grayish layer with large square pixels will appear in its place. This happens in version 6.1 and is as it should be.
In version 7.1, when I follow the same procedure as above, the photo does not completely erase, but, instead leaves a transparent ghost image behind , over the base pixel layer. Also, the white mask ( which should restore the photo when Paintbrushed over the photo), will sometimes instead, leave a white streak in the path of the Paintbrush tool. I am not sure if there are any other anomalies with Version 7.1.