VerticalMenuLevelProperties.setSubMenuHAlign

Sets the horizontal alignment of the menu level within each menu level container. For this property to be effective, menu item widths need to be set to a value less than the width of the menu container.

Supported values:

Value	Constant
Center	ControlConstants.HORIZONTAL_ALIGNMENT_CENTER
Left	ControlConstants.HORIZONTAL_ALIGNMENT_LEFT
Right	ControlConstants.HORIZONTAL_ALIGNMENT_RIGHT

Further documentation.