User blog comment:Kirkburn/Technical Update: March 3, 2015/@comment-452-20150303185952

Woah, the edit summary box is an input again! Better late than never! (I was just looking at those comments just a few hours ago, weird.)
 * ...however, it's not autocompleting for me in the preview right now, maybe it will work correctly tomorrow.
 * It's a problem with one of my scripts: When an Option element has a value of over 1024 characters, autocomplete stops working.

Anyone using any variant of the "Standard Edit Summaries" or "Standard Preloads" scripts should remember to collapse the right rail and update their CSS accordingly after this update.