[gtkada] coordinates

[yoann toussaint]

hello,  I 'm making a paint'like with gtkada and I want to get the  X 
and Y coordinates on mouse events.
my callbacks looks like :
function On_Shape_Drawingarea_Button_Press_Event
     (Object : access Gtk_Widget_Record'Class;
      Params : Gtk.Arguments.Gtk_Args) return Boolean;

is anyone knows how to get these coordinates with gtkada ?
yoann