The reason the Verse History dialog does not allow you to do what you want is because it wouldn’t give you what you want when you do it. I actually had many discussions with the designers explaining why this exact scenario couldn’t work correctly (at least not in all cases). I’m not great at explaining things, but I’ll try explain here.
First, realize the history for a project is complicated. Paratext keeps most of this complexity hidden, but with everyone changing things on their own computers and then doing a S/R at various points (and especially when using a USB stick that is passed around), the history for a project is not linear. Below is a screenshot of a program called TortoiseHg displaying the history of a real project. Each line shows a different history “path” that eventually gets sent to everyone else via merging. It shows how various history points are dependent on other history points, but which history points they are dependent on is determined by who a user last did a S/R with and the order the S/Rs happen.
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Because of the non-linear nature of the project history, there is no good way to display a list of changes in the Compare Texts and Verse History dialogs and have the user be able to choose one history point on one side of the dialog and choose the previous history point on the other side and give them what they want. Basically, the problem is that two different changes to a verse may have the same parent (this causes a merge conflict, but does happen, of course). If you would choose both of those changes in Verse History (because they are next to each other in the list of changes), you wouldn’t be seeing what changed in one, but the difference between the two changes - not what you were looking for.
In the Verse History dialog, this problem is made even worse because history points that anon421222’t contain a change to the verse in question are filtered out. This means there may be many project history points between the first and second item shown in the list in the Verse History dialog. If you were to choose the same two revisions in the Compare Texts tool, you would see all changes that were done between the two history points as well (probably not what most users would ever want).
This is why a button to go to the next difference does not exist in the Verse History dialog.
All that being said, with Paratext 7.6, we realized that for the Verse History dialog, what users really wanted, is to know when a change was made to a verse and who made it (what you were looking for) and that they might want the same thing in the Compare Texts dialog (i.e. what was changed for this history point). After much discussion, this birthed the new pseudo-history item called Baseline. Baseline is always the parent history point for the history point in the other pane. This new pseudo-history point gives users the ability to ask “what was changed in this revision” - significant, since before this change, users had to guess what the parent of a history point was to get this information correct. For the Verse History dialog, the history point representing the Baseline is probably not even included in the list of history points shown in the list.
Theoretically, if the user is comparing against the Baseline in the Verse History dialog, we could show the same in the Compare Texts dialog and that would give you what you wanted. However, it would require users to not change off of the Baseline comparison so it would probably be difficult trying to explain why that would be required in the UI.
EDIT: Forgot to mention that in 8.0, the Verse History dialog is now completely outside the scroll groups. There is now no way to view changes in other locations because any changes in other verses may be artificial (i.e. they may be caused by multiple other history points).