There are some controls specific to the Outline Panel.
Include/Exclude Outline Styles
This drop-down button controls which outline style rows are visible in the Outline panel.
Collapse All/Expand All
Expand 
Collapse
When clicked, this button expands or collapses all rows in the Outline panel. NOTE: If there is a mixed state of rows (some collapsed, some expanded), it will expand all the rows.
