Currently, the yellow revision can be navigated by the area below, the blue revision by the area above. Since the blue pointer may never surpass the yellow one, there are currently two unclickable areas, where the top (blue) or the bottom (yellow) area cannot be moved.
This leads to confusion for some users, since the "non-clickablility" suggests a broken tool. Furthermore, some people like to jump through revisions quickly for finding out where a change was introduced. Therefore, we want to make the areas clickable, keeping all existing metaphors
When a user hovers over the currently non-clickable areas, highlight the bar + show a ghost pointer as designed in [T172092]. Furthermore, highlight the bar and show a ghost for the other pointer as well, with an offset of one to the first one. That means, the end result should be like the one pointer having pushed the other pointer with it.
When the user then clicks on the highlighted bar, both pointers move to the indicated positions.
If the user switches from top to bottom or vice versa, the new highlighting disappears and we are back to the currently implemented behavior