This is a Third-party Addon.
Please use carefully on data that is backed up, and help make it better by reporting any comments or problems to the author, or issues to the bug tracker
The Split Views addon is a set of views that replicate all of the standard views, but adds a gramplet pane to each.
All of the views appear under the view category Split Views and by default comes with a ToDo Gramplet. You can customize each split view by right-clicking on the Gramplet Pane, and using the Configure View option.
Each view can be configure to have the panes running vertical or horizontal.