ghost/core/client/mixins/dropdown-mixin.js

/*
  Dropdowns and their buttons are evented and do not propagate clicks.
*/
var DropdownMixin = Ember.Mixin.create(Ember.Evented, {
    classNameBindings: ['isOpen:open:closed'],
    isOpen: false,

    click: function (event) {
        this._super(event);

        return event.stopPropagation();
    }
});

export default DropdownMixin;