If an image includes caption text which is too long to be displayed, there is currently no way to see the entire caption text. For example: http://xkcd.com/1435/
See entire caption text where?
Created attachment 8506887 [details] Example of cut off image caption text The popup menu which is shown when an image is long pressed has the caption text, if there is any, as the header text. If the caption text is too lengthy to fit within the header then there is no alternate way of viewing the rest of the text
There's actually an add-on for this: https://addons.mozilla.org/en-US/android/addon/total-title/ But yes, very frustrating for the xkcd case!
I think this is a duplicate of #768291. (Though this bug has more useful information in it than the older one.)