Optional alignmentThe content alignment of the layout.
Possible values are documented in SplitLayout.Alignment.
The default is 'start'.
Optional orientationThe orientation of the layout.
Possible values are documented in SplitLayout.Orientation.
The default is 'horizontal'.
The renderer to use for the split layout.
Optional spacingThe spacing between items in the layout.
The default is 4.
An options object for initializing a split layout.