User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0 Build ID: 20170722072631 Steps to reproduce: 1. Get the overflow menu icon to show up by pinning an item, say the home button, into it. 2. Go into the Customize mode, and add a flexible space onto the nav-bar. Exit Customize mode. 3. Right click this flexible space. Actual results: 1. There is a "Pin to Overflow Menu" item on the menu, and it is not disabled. 2. Clicking it doesn't remove the flexible space, but the something-was-pinned-to-overflow-menu animation plays out. Expected results: The "Pin to Overflow Menu" item should probably be disabled, as per https://bugzilla.mozilla.org/show_bug.cgi?id=1366813#c0 ("you can only add flexible spacers to toolbars, not panels")

Comment on attachment 8890428 [details] Bug 1383458 - disable pin to overflow / move to panel for flexible spacers (and other special items), https://reviewboard.mozilla.org/r/161532/#review166838 ::: browser/components/customizableui/test/browser_photon_customization_context_menus.js:436 (Diff revision 1) > }); > + > +// Bug 1383458 - shouldn't enable 'pin to overflow menu' for flexible spaces > +add_task(async function flexible_space_context_menu() { > + CustomizableUI.addWidgetToArea("spring", "nav-bar"); > + let springs = document.getElementById("nav-bar").querySelectorAll("toolbarspring"); document.querySelectorAll("#nav-bar toolbarspring")

Pushed by gijskruitbosch@gmail.com: https://hg.mozilla.org/integration/autoland/rev/b6da3839bc2a disable pin to overflow / move to panel for flexible spacers (and other special items), r=jaws

I have reproduced this bug with Nightly 56.0a1 (2017-07-22) on Windows 8.1 (64 Bit) This bug's fix is verified on Latest Nightly 56.0a1. Build ID : 20170801100311 User Agent : Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0

Verified on Windows, Mac, and Ubuntu.