On 1600x1200 screens the menu plus the revision box can easily occupy ~50% of the screen. This leads to almost any useful pipeline not fitting into the pipeline box. The overflow of the pipeline elements is cut off hard by the pipeline box without any indication to the user of this occurring, unless the box is cutting right through an element making it obvious to the user that something is missing.

The onliest indication of the overflow is an horizontal scroll bar at the bottom. This scroll bar is only noticeable once one has scrolled down below the last job in the pipeline queue. Since pipeline potentially contain hundreds of runs the scroll bar is out of reach in most scenarios. Common use cases will require the user to manipulate one of the jobs at the top of the pipelines list. So to actually use UI elements the user will have to scroll all the way down, scroll his way to the correct job and then scroll all the way up again. Using arrow keys to scroll the pipeline is possible but not convenient.

To alleviate the issue I would suggest the following improvements:

1. Job boxes should have a reasonable maximum width and grow to the bottom if an element needs more space than provided.
2. The display of the menu should be optional, since pipelines tend to require lots of horizontal space.
3. If the menu is present it should scroll with the pipeline horizontally. Currently it scrolls vertically already creating lots of negative space on the left side once it has scrolled out of the view port. Additionally it creates a large unused area on 5:4 screens when manipulating the pipeline elements.
4. The horizontal scroll bar should always be visible in the viewport if it is required. The pipeline is used a lot more horizontally than vertically. Scrolling down through the entire pipeline history is a lot less common than to access the last job in the pipeline. Horizontal scrolling should thus be more prominent than it is now.