Explanation of problem:
If you open the sample with a document with several pages and some are very wide and some are not and make an annotation on the wide page this causes all other annotation comments to be aligned with the one that is the furthest out. The problem is that as a user you may not see or notice that the annotations have comments because they are off screen. You can scroll over to the comment and this is an extra annoying step.
I've attached a video illustrating this problem.
This explains the video:
At 0:00 you can see I am at the top of the document and the comments are shown close to the page
At 0:03 I scroll down the document. In the background page 5 is loaded and the comments disappear off the right-hand side of the screen. I have to use the horizontal scroll bar to reposition the display. If page 5 had been even wider, I wouldn’t have been able to see the page and the comment at the same time
I continue to scroll down until 00:15 when the comment on page 6 moves closer to the document for a fraction of a second then disappears out of view again, so I have to use the horizontal scroll bar to reposition the display
At 00:26, the comments snap back to be close to the document again, and from here down, everything is normal again.
So there are really 3 usability problems:
1. having the comments a long way from the page makes it difficult to visually associate them with the annotations
2. having to adjust the horizontal scrollbar to keep both in view
3. if page 5 had been even wider, it would not have been possible to keep the comments and the document in view at the same time