Accessor of the hover-selection of the gtk-tree-view class.
The gtk-tree-view-hover-selection slot access function returns whether hover selection mode is turned on for the tree view.
The (setf gtk-tree-view-hover-selection) slot access function enables or disables the hover selection mode of the tree view. Hover selection makes the selected row follow the pointer. Currently, this works only for the selection modes :single and :browse.