-#ifdef __WXGTK20__
-    // Transitions for 3state checkbox must be done manually, GTK's checkbox
-    // is 2state with additional "undetermined state" flag which isn't
-    // changed automatically:
-    if (cb->Is3State())
-    {
-        GtkToggleButton *toggle = GTK_TOGGLE_BUTTON(widget);
-
-        if (cb->Is3rdStateAllowedForUser())
-        {
-            // The 3 states cycle like this when clicked:
-            // checked -> undetermined -> unchecked -> checked -> ...
-            bool active = gtk_toggle_button_get_active(toggle);
-            bool inconsistent = gtk_toggle_button_get_inconsistent(toggle);
-
-            cb->m_blockEvent = true;
-            
-            if (!active && !inconsistent)
-            {
-                // checked -> undetermined
-                gtk_toggle_button_set_active(toggle, true);
-                gtk_toggle_button_set_inconsistent(toggle, true);
-            }
-            else if (!active && inconsistent)
-            {
-                // undetermined -> unchecked
-                gtk_toggle_button_set_inconsistent(toggle, false);
-            }
-            else if (active && !inconsistent)
-            {
-                // unchecked -> checked
-                // nothing to do
-            }
-            else
-            {
-                wxFAIL_MSG(_T("3state wxCheckBox in unexpected state!"));
-            }
-            
-            cb->m_blockEvent = false;
-        }
-        else
-        {
-            // user's action unsets undetermined state:
-            gtk_toggle_button_set_inconsistent(toggle, false);
-        }
-    }
-#endif