New Delhi, Nov. 11 -- Amazon's latest Kindle firmware, version 5.18.6, looks routine at first glance with the usual nods to performance improvements and bug fixes. Look closer and there is a small but genuinely helpful change. Long pressing an internal link now opens a preview window so you can check a footnote or a referenced section without leaving the page you are on. It is a simple addition that pays off in reference heavy books such as encyclopedias, travel guides, magazines, and textbooks where back and forth navigation has always felt clumsy.

This release fits a broader pattern. Over the past few months Kindle software has picked up quiet, reader focused touches. In June, extra spacing controls for words, characters, and paragraph...