Add track_visibility='onchange' on available_in_pos

pos_usability/__init__.py

@@ -1 +1,3 @@
 # -*- coding: utf-8 -*-
+
+from . import product

pos_usability/product.py

@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+# © 2017 Akretion (Alexis de Lattre <alexis.delattre@akretion.com>)
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import fields, models
+
+
+class ProductTemplate(models.Model):
+    _inherit = 'product.template'
+
+    available_in_pos = fields.Boolean(track_visibility='onchange')