I finally got around to check the features of “x”–I am not sure how to deal with those missing horizontal and vertical arrangements yet–but I have tried the “button” after bringing a “jpg” image in the “Files”, and specifying that file as “Background Picture” for the button, and it seems to work.
Then, I converted the jpg to png, and loaded it up the same way. The screen display shows it properly. I haven’t tested how it would look on the android device, however; but as far as I can see, all seems to be working.