Thanks for making this. I've wanted this utility since 2013 when I drew a loading picture for Paradroid.
A few bugs: "Scroll X position" should be "Scroll Y position". You say Y in the PDF.
I sometimes get a corrupt character in the scroll, though I always get a glitch at the end and lose the first character when it loops.
And some suggestions:
The flashing might look better if it never went black (maybe an option?), or let us edit the colours it cycles through.
More characters in the scroll would be good (I used every last one).
It would be good to be able to load in a previously saved pic with scroller, so it could read in the text and settings so you could make a change instead of doing it all again.
Now I just have to find somewhere to send my version with loading picture and "readme" scroller.