If you comment on an initially-hidden line, it is hidden from view on subsequent page loads; even if you arrive via the deep link. So, basically, you're wasting your time.
Also annoying is you cna't reveal the whole file in one click, in the initial case I have to click expand three times in a row to get to the comment.
Steps to reproduce: 1. open a Pull Request with a long file 2. expand an area of the file that wasn't edited 3. comment on a line in the initally-hidden area 4. copy the deep link 5. open a new window to that deep link - comment is not revealed (screenshot 1) 6. scroll down the relevant file - comment still not revealed (screenshot 2) 7. expand the file until you find the comment (screenshot 3)
Page where I identified the problem: https://bitbucket.org/atlassian/aui-archive/pull-request/150/aui-974-first-cut-of-a-soy-servlet/diff
The comment is in auiplugin-tests/src/main/resources/atlassian-plugin.xml