Spacer properties

type	(string) the type of a control, set it to "spacer"
name	(string) the name of a control
id	(string) the id of a control, auto-generated if not set
width	(string|number|"content") the width of a control
height	(string|number|"content") the height of a control
padding	(string|number) sets padding between a cell and a border of the Spacer control
css	(string) adds style classes to a control
hidden	(boolean) defines whether a control is hidden