gtk:tree-view-expander-column (object)

object -- a gtk:tree-view widget
column -- a gtk:tree-view-column object for the column to draw the expander arrow at, or nil

The accessor for the expander-column slot gets or sets the column that is the expander column. It must be in the tree view. If the column argument is nil, then the expander arrow is always at the first visible column.

If you do not want expander arrow to appear in your tree, set the expander column to a hidden column. The gtk:tree-view implementation is deprecated since 4.10. Please do not use it in newly written code.