I would like a custom "emptybox" whose height can be chosen, but whose width and position is always the same: I would like the boxes to always extend through the full width of the document (from the left margin to the right margin).
So far I have this command:
\newcommand{\emptybox}[1]{\framebox[\textwidth]{\rule[-1em]{0cm}{#1}}}
But the problem is that the position of the box depends on where I call it. For instance if I use \emptybox inside an enumerate, the box will appear too much to the right.
Feel free to suggest a command not based on the one I gave, which does not do the job anyway. Thanks!

\linewidth, starts at the left margin but the vertical position may vary still? – Mar 31 '17 at 14:52