sixel preview writes out of bounds

[andy29485]

My preview script outputs sixels (using chafa) and sometimes helper text after the sixel image with extra metadata (album art + song info for music, thumb + streams info for videos, etc...). Prior to r32 sixel wasn't supported (thanks for adding it btw!), so I used the lf-sixel fork (which had it's own set of bug, but supported my previews).

To reproduce set your preview script to (doesn't matter what the image is):

chafa -f sixel example.png
echo hello # any text here will do

Example of the problem (ignore the fact that the file isn't selected, I switched windows to take the screenshot):

Expected result (using lf-sixel):

[catthegirl]

I looked through nav.go where the preview function is defined to see if I could help figure out your issue. I think what's going on behind the scenes is that the output since the previewer output starts with the sixel prefix the entire output is being rendered as though it were a part of the image rather than using the normal text rendering. It seems like lf and lf-sixel use an entirely different approach to sixel and that's why it works as expected on lf-sixel. Btw sorry if this isn't too helpful, I'm very inexperienced with open source contributions.