Accessor of the show-expanders of the gtk-tree-view class.
The gtk-tree-view-show-expanders slot access function returns whether or not expanders are drawn in the tree view.
The (setf gtk-tree-view-show-expanders) slot access function sets whether to draw and enable expanders and indent child rows in the tree view. When disabled there will be no expanders visible in trees and there will be no way to expand and collapse rows by default. Also note that hiding the expanders will disable the default indentation. You can set a custom indentation in this case using the gtk-tree-view-level-indentation function. This does not have any visible effects for lists.