Navigation Pane Splitter
The splitter is displayed above all visible group headers. End-users can drag it to show more or fewer group headers.

The table below lists the main members which affect the element’s specific characteristics:
| Characteristics | Members |
|---|---|
| Availability | NavigationPaneView.IsSplitterVisible |
| Command | NavigationPaneCommands.ShowFewerGroups, NavigationPaneCommands.ShowMoreGroups |