Function gdk_sys::gdk_drag_begin_from_point

pub unsafe extern "C" fn gdk_drag_begin_from_point(
    window: *mut GdkWindow, 
    device: *mut GdkDevice, 
    targets: *mut GList, 
    x_root: c_int, 
    y_root: c_int
) -> *mut GdkDragContext

This is supported on crate feature v3_20 only.