fix select2 plugin inside jquery ui dialog

select2-fix-jqueryui-dialog

dialog = $( "#dialog-form" ).dialog({
autoOpen: true,
height: 300,
width: 450,
modal: true,
  open: function () {
	if ($.ui && $.ui.dialog && $.ui.dialog.prototype._allowInteraction) {
	    var ui_dialog_interaction = $.ui.dialog.prototype._allowInteraction;
	    $.ui.dialog.prototype._allowInteraction = function(e) {
	        if ($(e.target).closest('.select2-dropdown').length) return true;
	        return ui_dialog_interaction.apply(this, arguments);
	    };
	}
  },
  _allowInteraction: function (event) {
      return !!$(event.target).is(".select2-input") || this._super(event);
  }		      
});