The problem is that you are having two so called PDF annotations defined at almost the same place. One for the tooltip and another one for the hyperlink, which is technically also a PDF annotation.
You can switch off the hyperlink with:
\usepackage[colorlinks=true,draft]{hyperref}
So in this case, you can only have the one without the other!
How about using PDF text annotations instead?


\documentclass{article}
\usepackage[colorlinks=true]{hyperref}
\usepackage{pdfcomment}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{Bli74,
author={Blinder, Alan S.},
year={1974},
title={The economics of brushing teeth},
}
\end{filecontents}
\usepackage{usebib}
\newbibfield{author}
\bibinput{\jobname}
\makeatletter
\let\@internalcite\cite
\renewcommand{\cite}[1]{%
\@internalcite{#1}\pdfcomment[icon=Help,author=Reference:]{\usebibentry{#1}{author} (\usebibentry{#1}{year})\textCR\usebibentry{#1}{title}}}
\makeatother
\begin{document}
This is a citation: \cite{Bli74}.
\bibliographystyle{apalike}
\bibliography{\jobname}
\end{document}
EDIT:
For a more subtle appearance, you can use empty and invisible PDF Markup Highlight annotations:

\documentclass{article}
\usepackage[rgb]{xcolor}
\usepackage[colorlinks=true]{hyperref}
\usepackage{pdfcomment}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{Bli74,
author={Blinder, Alan S.},
year={1974},
title={The economics of brushing teeth},
}
\end{filecontents}
\usepackage{usebib}
\newbibfield{author}
\bibinput{\jobname}
\makeatletter
\let\@internalcite\cite
\renewcommand{\cite}[1]{%
\mbox{%
\@internalcite{#1}%
\hbox to 0pt{%
\raisebox{1ex}{%
\pdfmarkupcomment[color=yellow,opacity=0,author=Reference:]%
{}%
{\usebibentry{#1}{author} (\usebibentry{#1}{year})\textCR%
\usebibentry{#1}{title}}}}}%
}%
\makeatother
\begin{document}
This is a citation: \cite{Bli74}.
\bibliographystyle{apalike}
\bibliography{\jobname}
\end{document}
EDIT2:
For viewers without additional marker, you can use your own marker like a tiny question mark. You should also increase opacity
.
\let\@internalcite\cite
\renewcommand{\cite}[1]{%
\mbox{\textcolor{blue}{%
\@internalcite{#1}%
\ifpc@gopt@final\else%
\hbox to 0pt{%
\raisebox{1ex}{\tiny%
\pdfmarkupcomment[color=yellow,opacity=0.5,author=Reference:]%
{?}%
{\usebibentry{#1}{author} (\usebibentry{#1}{year})\textCR%
\usebibentry{#1}{title}}}}%
\fi%
}%
}%
}%
\makeatother

EDIT3:
Or the same again with a tooltip:

\makeatletter
\let\@internalcite\cite
\renewcommand{\cite}[1]{%
\mbox{\textcolor{blue}{%
\@internalcite{#1}%
\ifpc@gopt@final\else%
\hbox to 0pt{%
\raisebox{1ex}{\tiny%
\pdftooltip[color=yellow,opacity=0.5,author=Reference:]%
{\fboxsep1pt\fcolorbox{blue}{yellow}{?}}%
{\usebibentry{#1}{author} (\usebibentry{#1}{year})\textCR%
\usebibentry{#1}{title}}}}%
\fi%
}%
}%
}%
\makeatother
Best Answer
The package
natbib
redefines the\cite
command with optional arguments that do exactly what you are asking for. Here is an example:The output looks like this:
If you prefer author-year citation style, you can remove the
[numbers]
option when loading the package, and you can replace the square brackets by round brackets with the option[round]
.