Well I finally have a map viewer. Its just simple click/double click tool I would like anyone interested to give it a try.
I am still codifying how to handle importing a screen but hit "load" and it will load up a map I've already imported for you to try out.
It seems to work fine in Chrome or Edge but wonky in Firefox as regards dragging the map around.
If you toy with the debug stuff- its not all neccesarily stable.
The menubar is ugly but I don't have the patience at the moment to make it better yet. Right-Click "Menubar" is your friend (toggle visibility).
Enjoy !