[Affected versions]: - Firefox 61.0a1 (20180419100148) [Affected platforms]: - Win 7 64-bit - Win 10 64-bit [Steps to reproduce]: 1.Flip “extensions.webextensions.tabhide.enabled” to true. 2.Open multiple tabs. 3.Hide one tab. 4.Press the ”Alt” button. 5.Observe the “v” button positioning. [Expected results]: - The button is displayed under the “x” button of the browser. [Actual results]: - The position of the the “v” button is not changed from his current positioning when the menu bar is displayed. [Notes] - Right click -> select “Menu Bar” -> The “v” button is moved under the “x” button. - This issue is reproducible only on Windows.

I feel like this is probably the expected behaviour. It would be fairly jarring to have the tabs drop move around when you press the alt key. Nothing related to this should have changed with regards to hidden tabs. I'm going to resolve this invalid but if you test on release or beta and this isn't how it's supposed to work can you please reopen?

Unfortunately, I can reproduce the issue on Firefox 59.0.2 (20180323154952) and Firefox 60.0b15 (20180423171039) under Win 7 64-bit and Win 10 64-bit. I will reopen the bug as you mentioned in comment1.

The behaviour looks the same on release to me so I think this is working as expected. We don't want things to jump around too much when the user presses alt so the tab strip doesn't take the full width.