>>> My Info: Win7_64, Nightly 49, 32bit, ID 20160526082509 STR_1: 1. Install attached "extension 1" (v.1.9.9.3, the latest version of "Tab Counter" as of 2016.10.10) 2. In customize mode, move home toolbarbutton after "All tabs" dropmarker in tabs toolbar, then move toolbar item created by "Tab Counter" between "All tabs" dropmarker and home toolbarbutton 3. Open new window AR: Sequence of last 3 items in tabs toolbar: "All tabs" - "Home" - "Tab Counter" ER: Sequence of last 3 items in tabs toolbar: "All tabs" - "Tab counter" - "Home" This is regression. Nightly (2014-01-01) is 100% unaffected. Nightly (2015-01-01) - 100% affected Somewhere in the middle it's reproducible, but not 100%, so finding regression range may be hard. If you visited this bug to find regression range and encountered the same problem, at least confirm that 2014-01-01 is unaffected and 2015-01-01 is affected. In Step 1 you can install from the link: https://addons.mozilla.org/en-US/firefox/addon/tab-counter/

Mass-closing old Extension Compatibility bugs that relate to legacy add-ons or NPAPI plug-ins. If you think this bug is still valid, please reopen or comment. Sorry for the bug spam, and happy Friday!