I have problem with my custom widget. when widget starts, it stays on another product. It needs pager refresh to reload with correct parameters. How to reload automatically my widget when I am changing product form view?

openerp.mymodule = function(instance, local) {    
var _t = instance.web._t,        
_lt = instance.web._lt;    
var QWeb = instance.web.qweb;    

instance.web.form.widgets.add('mywidget', 'instance.mymodule.WidgetM');    
local.WidgetM = instance.web.form.AbstractField.extend({
start: function() {                
this.$el.html(QWeb.render("WidgetTemplate"));                

return this._super();            
}
});
}

Thanks