Strange appearance of tooltips produced by pdfcomment

Question

Tooltips can be generated with pdfcomment package. However, they lead to some weird behavior if one clicks on a tooltiped item: the item becomes highlighted and "checked" (checked in Acrobat Reader 9 in Debian and Acrobat Reader X in Windows XP). So, it looks more like a "checkbox":

See an example below

\documentclass{article}
\usepackage{pdfcomment} 

\newcommand\MyShortCut[3]{\newcommand{#1}{\pdftooltip{#2}{#3}}}

\MyShortCut{\textthing}{tooltip here}{just an example}
\MyShortCut{\Td}{\tau_\textrm{d}}{reptation time}
\MyShortCut{\Tr}{\tau_\textrm{R}}{Rouse time}

\begin{document}
Use pdflatex to compile, then open in Acrobat Reader and
put the mouse pointer above $\tau$'s

\[
\Td = 3 Z \Tr
\]

Or in text \textthing.

\end{document}

Question: is there a better way to achieve my goal: to have a tooltip when a mouse pointer is over a piece of text or a variable? Without any side effects, like the ones described above. Ideally, with hyperref only, so I do not need to load extra packages (\href does something similar).

Answer 1

This bug has been fixed in version 2.3a of pdfcomment, which is available on CTAN and can be obtained by updating your TeX distribution. The manual fix provided in this answer is not necessary any more!

Apparently there's a bug in pdfcomment which causes the weird appearance of the tooltips: There is a spurious slash in the specification of the field flags (pdfcomment.sty, l. 2967), so Adobe Reader uses the default value for this property and creates a checkbox instead of the desired pushbutton. The following example includes a fix for this:

\documentclass{article}
\usepackage{pdfcomment}
% Fix incorrect display of tooltips (http://tex.stackexchange.com/a/74340/3323)
\makeatletter
\renewcommand{\pc@annot@tooltip}%
{%
  /TU (\pc@pdfenc@contents)\space%
  /T (tooltip \thezref@unique)\space%
  /C [0 0 0]\space%
  /FT/Btn\space%
  /Ff 65536\space%
  /H/N\space%
}%
\makeatother

\newcommand\MyShortCut[3]{\newcommand{#1}{\pdftooltip{#2}{#3}}}

\MyShortCut{\textthing}{tooltip here}{just an example}
\MyShortCut{\Td}{\tau_\textrm{d}}{reptation time}
\MyShortCut{\Tr}{\tau_\textrm{R}}{Rouse time}

\begin{document}
Use pdflatex to compile, then open in Acrobat Reader and
put the mouse pointer above $\tau$'s

\[
\Td = 3 Z \Tr
\]

Or in text \textthing.

\end{document}

Tooltip appearance:

Like this, no strange boxes are shown around the tooltip area on hover, and it's not possible to highlight or tick it.