how to write hidden comments on LaTeX

http://tex.stackexchange.com/questions/11177/how-to-write-hidden-notes-in-a-latex-file

もちろんアレンジして使うことも可能。
段落分けせず、コメントを[ ] で囲む場合は、最後の行を

 % Select what to do with command \comment:
 % \newcommand{\comment}[1]{}  %comment not showed
 \usepackage{xcolor}
 \newcommand{\comment}[1]
 {{\bfseries \color{blue} [#1]}} %comment showed

に書き換えればよし。