# Black square margin GFX bug

I've run across a GFX bug that seems to has something to do with text formatting and line breaks. It is a black box the size of a character, that appears in the right margin. It looks like this:

On my homepage, you can view the entire document, as well as the LaTeX source. (It is on page 21.)

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You have the draft option specified in your \documentclass command. This puts marks in the margin to point out places where TeX has put text outside the margins. See What does draft mode change? –  Alan Munn Dec 22 '12 at 5:22
What is this GFX? –  Heiko Oberdiek Dec 22 '12 at 5:38

You are using option parfill of package parskip. That requires a minimum space (30pt) at the end of the last line of a paragraph. In your case the paragraph has two lines and the second line is 13.1239pt too long for the minimum space of 30p. Therefore TeX prints an overfull \hbox warning and because of option draft of document class report the overfull \hbox is marked with a overfull rule with width 5pt.

Solutions:

• Resolving the overfull \hbox warning.
• Removing global option draft.
• Smaller minimum space of option parfill of package parskip:

\usepackage[parfill]{parskip}
\setlength{\parfillskip}{16pt plus 1fil}

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Thanks, also, @AlanMunn said the same. I removed the draft option, and it worked. I browsed the document, and everything seemed OK, so I guess removing that options won't have any other effects except getting rid of that box, which is what I want? –  Emanuel Berg Dec 22 '12 at 5:46