When i copy & paste multi-line text (from X11 clipboard) into Github/gist web inputbox i can see my text properly formatted (for a glimpse of a second). Then gist immediately removes all line breaks and fits everything into one line (see pic below). Copying text from Firefox to Firefox (even one liners) are split into several lines though.
How can i disable this text processing? Its not working properly.
Arch Linux, xfce, Firefox 58.0.2