OptionalalignmentThe content alignment of the panel.
The default is 'start'.
OptionaldirectionThe layout direction of the panel.
The default is 'top-to-bottom'.
OptionallayoutThe box layout to use for the box panel.
If this is provided, the other options are ignored.
The default is a new BoxLayout.
OptionalspacingThe spacing between items in the panel.
The default is 4.
An options object for initializing a box panel.