Positioning hints for aligning the menu relative to a rectangle.
These hints determine how the menu should be positioned in the case that the menu would fall off-screen if placed in its ideal position.

For example, gdk.types.AnchorHints.FlipY will replace gdk.types.Gravity.NorthWest with gdk.types.Gravity.SouthWest and vice versa if the menu extends beyond the bottom edge of the monitor.
See gtk_menu_popup_at_rect (), gtk_menu_popup_at_widget (), gtk_menu_popup_at_pointer (), #GtkMenu:rect-anchor-dx, #GtkMenu:rect-anchor-dy, #GtkMenu:menu-type-hint, and #GtkMenu::popped-up.
Get anchorHints property.