Current histories typically include dozens of notes, updates, emails, scrolling through it you can't normally see more than one action. If you could minimize history events on the main incident/call page you could leave open the ones you want without having to switch to the full history view, it would make this area much more useful for review.
On the full history there is a expand/hide carrot for the histories, something like that would be great.
sidenote: If all the history items started off minimized except the latest history in this area and the data were not loaded until the item was expanded, you wouldn't need to load the whole history when you view the call as well so it would/could benefit the load on the server and sql for larger clients
with the word Expand History