I downloaded and testet your program. It looks nice and I realy would like to use the final version.

I found the following problems

- Fullscreen doesn't work
- When I click on "adapt to screen" the program crashes

I also have recommendations for 2 little but helpful features.
1. Hotkeys for "Next Page" and "Previous Page": Maybe "CMD + LEFT/RIGHT"

2. Zoomoption for "fit width": Adapt to screen is nice but in generally it means "adapt height" because the most screens are widescreen. So the result is that the text in the comic is to small to read on some displays. Especially on Notebooks.