The "watch -d" should higlight changes since previous command run.
 However, it sometimes keep highlighting on old parts of output,
 such error display is kept until end of run.

 Attached scrinshot demonstrates this behavior: refresh time is 5sec,
 but 2nd highlighed file was last changed 5 min ago.

 On SIGWINCH (change of window size) highlighting is restored to
 right one.