Documentation 
Section: gtk/GtkTooltips
gtk_tooltips_new ()

GtkTooltips*        gtk_tooltips_new                    (void);

Creates an empty group of tooltips. This function initialises a GtkTooltips structure. Without at least one such structure, you can not add tips to your application.
Returns : 	a new GtkTooltips group for you to use. 

Correct version:
It should also include information about how to manage the structure's memory. 

From this email, http://foo-projects.org/pipermail/xfce4-dev/2007-April/022965.html, I have the following information. It should be verified, and something similar should be included in the documentation.

"Ok, this is from memory, so I may not remember this correctly, but I
think it's like this:

"gtk_tooltips_new() creates a GtkObject with a floating reference. This
means that you either use it like that and call gtk_object_sink() to
free the object, or you take a reference (g_object_ref()), remove the
floating flag (gtk_object_sink()) and then to free the object you use
g_object_unref()."

Other information: