FAPI
A new form element in Drupal core
Heine Wed, 2009/01/28 - 09:48
This post was written for a development version of Drupal between 6 and 7. The queries and pager need conversion to DBTNG.
With Commit #167487, a new form element has been added to Drupal core (7.x) to provide an alternative means of selecting items. Now, next to 'select' (combobox, list), checkboxes and radios, core carries the 'tableselect' element. This element allows developers to easily create tables with selectable rows. Ideal for those situations where you have to provide a lot of data on the items to the user.

If you are familiar with the Drupal forms API you know the concept of form elements as the basic building blocks of any form. Drupal provides several types of elements, some rather straightforward (#type textfield), some more advanced (#type password_confirm).
It is also possible to define custom form elements that enable you to implement complex widgets with ease.