Expander
An Expander is a control that organizes objects by providing a heading and the ability to expand or collapse the contents.
SectionTitle
An expander’s Header property is used for the title and can be a string or other WPF element. The contents of an expander are configured in the Content property and are usually a Panel or Grid with children.
Important: The Expander control may not work as desired if its Height property is specified. Ensure the Height property is set to Auto.
See Common Controls to view the usage and description of the properties for this control.