Emacs whitespace-mode

I just found out about whitespace-mode. Very useful if whitespaces are of syntactic value. For example in Makefiles. Emacs’ makefile-mode already shows leading spaces as pink, but leading and trailing spaces might be problematic in other cases as well. The whitespace-mode shows all kinds of spaces, eight spaces are highlighted in bright yellow (“no tab”), tabs are also visualized, as are newline characters.