In app pdf viewer
Instead of a separate app.
Shemsedin Nursebo Salih commented
I have similar idea like the above post, that is, it is much better to have in app pdf viewer than one that popes up in separate window. Moreover, it would be definitely be easier to read through different articles when you have them as tabbed on the same window rather than having one window for each article or pdf file(as in Foxit reader, Mendeley).
Luis J. Manso commented
Are you talking about the Android app? If so, the title of the idea should specify that... Just in case, here is my upvote :-)