Feature request from bgalileo, posted on GitHub Jan 14, 2015
In Magento 1, there is no easy way to add a user-friendly product, category or customer selection widget to a custom form. There are ways to add the product, category, cms page and cms block chooser widgets to your form, but the process is neither well-documented nor obvious, and a customer chooser widget simply doesn't exist.
Since you often need to link information with specific customers, products or categories in custom modules, it should be easy to add a form element which allows the user to select one or multiple product/category/user IDs via the corresponding grids, which are then submitted together with the form.