diff --git a/xs/GtkBindings.xs b/xs/GtkBindings.xs
index 1f3e631..5ef0616 100644
--- a/xs/GtkBindings.xs
+++ b/xs/GtkBindings.xs
@@ -402,9 +402,17 @@ MODULE = Gtk2::BindingSet	PACKAGE = Gtk2::Object	PREFIX = gtk_
 
 =for apidoc
 Although C<activate> and C<activate_event> are C<Gtk2::Object>
-methods, as of Gtk 2.12 they will only actually invoke signals on a
-C<Gtk2::Widget>.  On a C<Gtk2::Object> the return is always false (no
-binding activated).
+methods, as of Gtk 2.12 binding sets are only associated with widgets
+so on an object as such the return is always false (no binding
+activated).
+
+Further, although C<activate> and binding sets are both expressed in
+terms of keyvals, internally the lookup is by keycode.  If a keyval
+cannot be generated by at least one keycode/modifier combination (see
+L<Gtk2::Gdk::Keymap>) then it cannot be activated.  In particular this
+means keyvals like C<Pointer_Button1> which are not actual keys cannot
+be dispatched by C<activate> (returning false for no binding
+activated).
 =cut
 gboolean
 gtk_bindings_activate (object, keyval, modifiers)
