Expands the selected categories to reveal subcategories. This works the same way as clicking on the arrow icon to the left of the parent category. (Disabled if no parent categories are selected.)
TIP: Expanding All
To expand all categories under a parent category, press the ALT / Option key when clicking on the category arrow icon.
Expand All
Expands all parent categories to reveal subcategories. (Disabled if all parent categories are already expanded.)
Collapse
Collapses the selected parent categories to hide subcategories. This works the same way as clicking on the arrow down icon to the left of the parent category. (Disabled if no expanded parent categories are selected.)
TIP: Collapsing All
To collapse all categories under a parent category, press the ALT / Option key when clicking on the category arrow icon.
Collapse All
Collapses all parent categories to hide subcategories. (Disabled if all parent categories are already collapsed.)
ALT / 
Option key when clicking on the category arrow icon.
ALT / 
Option key when clicking on the category arrow icon.