Working With Model Items and Diagrams > Working with diagrams > Basics > Splitting diagram windows
  
Splitting diagram windows
You can view different parts of the same diagram simultaneously in adjacent panes by using split pane viewing. This is useful for viewing different areas of a large diagram. In particular, this type of view is applicable to Sequence Diagrams which tend to be wider than the normal screen view.
Split pane viewing is controlled by split boxes situated at the top right of the vertical scroll bar and bottom left of the horizontal scroll bar.
To split a view into two or four panes:
Drag the split bar to the required position on the scroll bar.
To remove the split:
Double click the split bar and drag it to the edge of the window.