Consider the following MWE to be compiled with `pdflatex' that attaches the `foo.tex' file to the PDF:

--8<---------------cut here---------------start------------->8---
\begin{filecontents*}{foo.tex}
\documentclass{article}
\begin{document}
Foo.
\end{document}
\end{filecontents*}
%
\documentclass{article}
\usepackage{xcolor}
\usepackage[color=black]{attachfile2}
\begin{document}
\textattachfile{foo.tex}{Link to `foo.tex'}.
\end{document}
--8<---------------cut here---------------end--------------->8---

The link is supposed to open `foo.tex' but:

1. Okular doesn't consider it as a link (the mouse pointer doesn't change to the finger when you hover above the link).
2. Nevertheless:
- a double (left) click  opens an empty annotation where you expect the attached `foo.tex' file to be open,
- a right click only allows to save the attached `foo.tex' file, not to open it.

By contrast, Adobe Reader and Evince do the expected job: a click on the link open the `foo.tex' file with the default `.tex` editor (Evince having the drawback to open it with a different name: `foo.tex.xxx', where `xxx' is a random string).




 `foo.tex.xxx'
instead, where `xxx' is a random string. The file open has the same
content as `foo.tex' but, because of its strange extension, is not open
as a `.tex' file by the underlying text editor.

Notice that Adobe Reader opens this file with the same name.

Reproducible: Always

Steps to Reproduce:
1. Compile the above file with `pdflatex`.
2. Open the corresponding PDF with Okular.
3. Double click on the text: "Link to ‘foo.tex’".

Actual Results:  
An annotation is open.

Expected Results:  
The attached file should be open in the (external) default editor for `.tex` files.