There is a bug in diagram scrolling in a couple of situations.

Open the TreeLayout.exe sample in a two monitor setup.

Problem 1: Maximize the program in the left monitor. Left click on the diagram to select, and drag to the right until it begins to scroll, then try to drag back to the left to scroll back. It won't let you scroll back to the left.

Problem 2: Move the program to the right monitor and maximize it. Now try to select and drag to the right to scroll the diagram, it won't let you.

None of these problems happen when the window is not maximized, or if there is any sort of padding or control in that direction. For instance, it never breaks when moving up because the title bar is always there.