The PanelBar supports various expand modes.
The expand modes are:
single—Expands only one item at a time. If you expand an item, the item that was previously expanded is collapsed.
multiple(default)—Expands two or more items at a time. Items can also be toggled.
full—Expands only one item at a time and requires you to set the
heightproperty. The expanded area occupies the entire height of the PanelBar.
To configure the expand modes, use the expandMode property of the PanelBar.