Problem/Motivation
An issue occurs when more than 100 items exist in the root of the menu or under a single parent item, or items exist with a weight outside of -50..50 (causing overflow when trying to fit that weight into the select form element).
Proposed resolution
A patch was drafted using the parameter ($delta) to the recursive helper function
_menu_overview_tree_form() to build the menu tree form. $delta first gets set in menu_overview_form() to the total number of links in the menu
The book and taxonomy modules address this issue in these ways.
A possible solution includes a generic procedural function that takes a minimum value and a maximum value and returns the recommended FAPI delta based on that.
The interdiff file is available.
The last patch failed testing with these results.
Remaining tasks
Remaining tasks might include a more integrated solution across the implementation of menu instances, partly described by Dries, D7 backport, and testing.
Unit testing any new procedural function would be a need.
User interface changes
Row weights is described as being criticial in this issue.
Select boxes/widget in text fields are related.
Drop down menus and node forms were also orginially discussed in the issue posting.
API changes
Entity form controllers now appear in core.