In a details page, usually any changes done to the fields will not be applied until the user clicks the Update button. However, if the page contains an association table, any addition/deletion to the table will be applied immediately. To avoid any confusion, the user is now required to save or reset all changes to the page before modifying the association. A dialog box will appear if the page contains any unsaved changes.
http://www.freeipa.org/page/UI_Unit_Tests