I use TeXworks 0.4.5 on Windows 8 and I've noticed quite an unpleasant bug. When having a rather long document (~2000 lines), some parts of the source code are not visible. Yet, they are typeset in the generated pdf.
Googling for a while took me here and here. I tried everything recommended on both of these links, such as disabling babel package, turning syntax coloring off, etc. Nothing didn't help. Full document's ctrl+a -> ctrl+c -> ctrl+v didn't help either. When I create a copy of .tex file and open the copy, problem's gone (for that particular passage I'm looking at). However, I can not be sure about the rest of the document.
Have you ever heard of something similar?
EDIT: Getting line numbers on (Format -> Line numbers) seems to make invisible parts visible once again. Still, it shouldn't be necessary... (I actually find line numbers distracting, so it's not a much of solution for me.)