OptionalalignmentThe content alignment of the panel.
The default is 'start'.
OptionallayoutThe split layout to use for the split panel.
If this is provided, the other options are ignored.
The default is a new SplitLayout.
OptionalorientationThe layout orientation of the panel.
The default is 'horizontal'.
OptionalrendererThe renderer to use for the split panel.
The default is a shared renderer instance.
OptionalspacingThe spacing between items in the panel.
The default is 4.
An options object for initializing a split panel.