gtk-tooltip-set-tip-area (tooltip rectangle)

tooltip -- a gtk-tooltip object
rectangle -- a gdk-rectangle instance

Sets the area of the widget, where the contents of the tooltip apply, to be rectangle in widget coordinates. This is especially useful for properly setting tooltips on gtk-tree-view rows and cells, gtk-icon-view widgets, etc.

For setting tooltips on the gtk-tree-view widget, please refer to the convenience functions for this: gtk-tree-view-set-tooltip-row and gtk-tree-view-set-tooltip-cell.