Sets the area of the widget, where the contents of this tooltip apply,
to be rect (in widget coordinates). This is especially useful for
properly setting tooltips on GtkTreeView rows and cells, GtkIconViews,
etc.
For setting tooltips on GtkTreeView, please refer to the convenience
functions for this: gtk_tree_view_set_tooltip_row() and
gtk_tree_view_set_tooltip_cell().
Since 2.12
Sets the area of the widget, where the contents of this tooltip apply, to be rect (in widget coordinates). This is especially useful for properly setting tooltips on GtkTreeView rows and cells, GtkIconViews, etc. For setting tooltips on GtkTreeView, please refer to the convenience functions for this: gtk_tree_view_set_tooltip_row() and gtk_tree_view_set_tooltip_cell(). Since 2.12