First of all, thanks for writing this library. I've built out several tools around street view calls, but your project is really impressive.
I really like how you are showing the grid of the tiles pulled for the zoom levels from 1-5. I'd like to suggest adding a feature to download the zoom level 1 images (left and right) to serve as a backdrop to the tile selection, perhaps as an additional button.
I may try to take a look at this and see if I can implement it for my own use as well.
Once again, thanks for putting together this great library.