User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0 Build ID: 20170805085114 Steps to reproduce: The <select> drop down menu is showing but not working in sidebar. (FF56.0b1 64bit) Tomislav suggested setting 'extensions.webextensions.remote' to false and after reloading the extension, the drop down menu worked fine in the sidebar. The default 'extensions.webextensions.remote' is true and users will not be expected to change it. related to: Bug 1190679

This has to be a very recent regression, I've got an addon that I test various things with including dropdowns like this. I didn't notice this the last time I looked (1-2 weeks ago at most). This also affects browser and page action. It does not seem to affect other dropdowns (e.g. datalist).

Not sure that title is accurate still. STR: - load an extension with a sidebar, browseraction and pageaction, all with a select dropdown - page/browser actions work fine if used first - use dropdown in sidebar - try page/browser actions again expected: - dropdowns work everywhere actual: - once you use the drop down in the sidebar, dropdowns do not work in any extension panel. Probably need to find the regression window, I'm fairly certain this wasn't an issue before.

OOP needs another attribute for the dropdown.

Comment on attachment 8897054 [details] Bug 1389495 support select in OOP sidebar, https://reviewboard.mozilla.org/r/168346/#review173566

Pushed by mixedpuppy@gmail.com: https://hg.mozilla.org/integration/autoland/rev/9f3981bb36b4 support select in OOP sidebar, r=kmag

I can reproduce this issue on Firefox 57.0a1 (20170814100258) under Wind 7 64-bit. This issue is verified as fixed on Firefox 57.0b10 (20171019140425) and Firefox 58.0a1 (20171020100426) under Wind 7 64-bit and Mac OS X 10.13. Using the STR from comment 2, the <select> drop-down is working if you use the drop-down from sidebar then the drop-down from the browser action. Please see the attached videos.