Perhaps worth looking at this thread :
https://www.mobileread.com/forums/showthread.php?t=62273
The libdjvu that tigran built for the Hanlin v3 was a great viewer for djvu files with excellent control over the display (IIRC it allowed different layers to be displayed).
The thread is quite old (2009) and the links to the source are now broken but someone might just have a copy.
BobC