I have been fixing dozens of problems with 140 ESR's GUI. Earlier today I fixed almost all of the problems with the search panel: Screenshot: [http://example.com https://forums.mozillazine.org/viewtopic.php?p=15008668#p15008668] Except one: I do not know how to detect when the default search engine has changed. I need to know how to detect when the default search engine changes so I can update the favicon and placeholder text by recalling my '''gui_fixes_search_favicon()''' function in userChrome.js. I'm an experienced web developer of 20+ years and would be grateful if someone could share their insight without the often "obligatory" cautionary tales 101 bit. Thank you in advance!