is an option for cells that specifies whether an opener icon is displayed next to the leading cell in a cell group to indicate whether the cell group is open or closed.
- With the default setting ShowGroupOpener->False, no icon appears next to the leading cell in a cell group.
- With the setting ShowGroupOpener->True, a triangular opener icon is displayed to the left of the leading cell. Clicking the icon opens or closes the cell group. The triangle points to the right when the cell group is closed and down when the cell group is open.
Introduced in 2007