Notes:
It is a bit of an edge case, please check the attached screen recording for a better understanding: https://streamable.com/su7rz

Affected versions:
Firefox Nightly 68.0a1 (2019-03-24)

Affected platforms:
Windows 7
Ubuntu 16.04
MacOS is not affected

Steps to reproduce:

• Launch latest Firefox Nightly with a new profile (make sure the blue dot appears on the firefox account icon)
• Resize the window close to the point where the "More tools.." icon is displayed in the toolbar
• Click on the Firefox Account icon
• Resize the browser more until the "More tools.." icon is displayed
• Click on the above mentioned icon
• From the menu, click on the Firefox Account option

Expected result:
The "Turn on Sync" option is displayed.

Actual result:
The Firefox Account option will remain highlighted with a dark grey (as if it would be constantly clicked on). Clicking on it will not lead to the "Turn on Sync" page.

If you move the library button to the right of the account/sync button, does the same thing happen with that button?

Are there any errors in the browser console (ctrl-shift-j) ?

Hi Gijs,

The same issue happens if I move the library button to the right of it. No errors in browser console.

Timea, can you find when this regressed (testing with the library button)?

FWIW, I doubt this is a (recent) regression, but it was originally reported for the accounts button, which is new in 68.

I don't believe it to be a regression at all. Used as good build 2019-03-18 (date accounts button landed) and as bad the following day 2019-03-19 as it was affected.
Mozzregresion leads to Bug Bug 1535995, but I don't see how some fix for crashes (LSNG maybe?) could affect this.
So again..this might have been like this from the start.

(In reply to Timea Babos from comment #6)

I don't believe it to be a regression at all. Used as good build 2019-03-18 (date accounts button landed) and as bad the following day 2019-03-19 as it was affected.
Mozzregresion leads to Bug Bug 1535995, but I don't see how some fix for crashes (LSNG maybe?) could affect this.
So again..this might have been like this from the start.

I'm a bit confused now. The point of the question in comment #1 was to figure out if the Library button has the same issue.

The Library button is much older than the accounts button (ie was around long before 03-18 this year), and indeed in my testing seems to have the same issue (at least that it keeps its greyed-out background) as the accounts button.

Can you see if this is a regression with the library button?

Let's rewind a bit as we are both confused. In Comment 1 I understood and tested what happens with the Account button if the library one is moved to its right side. Didn't actually catch the idea to test the library button itself at that point but now I verified it and results are as follows:

• Library button will be constantly highlighted (as if it is constantly clicked down) but it is functional. This happens if it is moved to the overflow menu - by resizing window - whether the library icon is at it's default location or moved elsewhere. Here is a screen recording: https://streamable.com/7mvsr

Even tho it looks similar, the library option is still functional..unlike the Account one that will remain blocked unless the browser is restarted.

Will try to get the regression range for the library button case if that helps. Working on it...leaving the NI? for this one me.

Went back to Fx 55.0a1 when the library button was introduced via Bug 1354155 and the this issue can be reproduced there too.
Moved the library to the toolbar of the browser using the customize mode and tested by following the same steps, recording: https://streamable.com/2n28s

Nightly BuildID: 20170609030207

Let me know if there is anything else I can help with.

Thanks for digging deeper on this. I'm setting this as P5 since this bug is not very easy to reproduce and users aren't likely to be resizing the window with the panel open.