STR: 1. Open a long page in Firefox on Mac. 2. Zoom or fullscreen the Firefox window. 3. Move the mouse pointer to the right edge of the screen. 4. Try to scroll the page using the trackpad. RESULT: The page does not scroll in Mac Firefox, but it does scroll in Chrome and Safari (and Windows Firefox). You can only scroll the page in Mac Firefox if the mouse pointer is hovering over the page, the scrollbar, or the left edge of the screen. I suspect this might be a regression from upgrading from OS X 10.11 to macOS 10.12 (Sierra). I'm pretty sure this used to work in Firefox, but all versions I've tested on my MacBook Pro running macOS 10.12 (all the way back to 40) have the same problem. I was not able to reproduce the bug on an iMac running OS X 10.11, but it's not really a direct comparison because the iMac has a different OS version and is using an external display and mouse scroll wheel (instead of a trackpad).

Andrei: Are you able to test this to see if you get the same results as Chris?

I have reproduced this issue using a late-2013 MacBook Pro with MacOS 10.12.1 updated from Mac OS X 10.11.6. This was reproduced on the following Firefox builds: - Nightly 52.0a1 (id: 20161110030211) - DevEdition 51.0a2 (id: 20161110004022) - Beta 50.0b11 (id: 20161027110534) - RC 49.0.2 (id: 20161019084923) - ESR 45.5 (id: 20161031153904)

(In reply to Alexandru Simonca, QA (:asimonca) from comment #2) > I have reproduced this issue using a late-2013 MacBook Pro with MacOS > 10.12.1 updated from Mac OS X 10.11.6. Do you happen to have a MacBook Pro running a version of Mac OS X earlier than 10.12? I'm not sure if this problem was first started after I upgraded from OS X 10.11 to 10.12 or whether this problem always existed and I just never noticed it before. <:)

I have just tested the same thing on Mac OS X 10.9.5 and it doesn't happen there. We will be installing another OS (fresh copy of 10.11) on this MacBook Pro later today and I will test it on that as well. Leaving the ni? for later.

You probably don't need to test 10.11. Since you've shown that the problem happens in 10.12 but not 10.9, we know there was an OS change. And since I only noticed it a few days after I upgraded from 10.11 to 10.12, it's probably safe to assume the OS change was in 10.12. :)

I agree but I also checked just to make sure and you're right; the issue does not reproduce in 10.11.

Too late to fix in 50.1.0 release

53 is affected, too. This bug is very annoying for Mac trackpad users.

Stephen, is this something you'd be able to look at? Sounds like a painful issue for macOS 10.12 users.

This is tracked as one of our platform integration bugs[1], but since this is marked as a P3 bug it hasn't bubbled to the top yet. Tracy, should this be a P1 or P2 instead? [1] https://wiki.mozilla.org/Platform/Integration#Widget:Cocoa

I'll move it up to p2 if that'll help get in a work queue. But scroll functionality isn't broken completely, only in this edge case. (oh, the pun)

Version due to Comment 2

Mass wontfix for bugs affecting firefox 52.

I can't reproduce this, Mac OS 10.12.3, MacBook Pro, in 53 beta. Andrei, can your team have a look to see if it's still reproducible in whichever version of 10.12 you use? Thanks. Markus, assuming this issue still exists can you find someone to work on it since we keep bumping the priority up?

This is still reproducible on my machine. I've gone ahead and debugged it and the fix is fairly simple.

Comment on attachment 8858480 [details] Bug 1313977 - Don't round fractional mouse coordinates up, because doing so might push them outside the window. https://reviewboard.mozilla.org/r/130446/#review133152

Comment on attachment 8858480 [details] Bug 1313977 - Don't round fractional mouse coordinates up, because doing so might push them outside the window. https://reviewboard.mozilla.org/r/130446/#review133160 ::: widget/cocoa/nsChildView.mm:4901 (Diff revision 1) > RefPtr<nsChildView> geckoChildDeathGrip(mGeckoChild); > > NSPoint locationInWindow = nsCocoaUtils::EventLocationForWindow(theEvent, [self window]); > > + // Use convertWindowCoordinatesRoundDown when converting the position to > + // integer screen pixels in order to ensure that coordinates whach are just nit: s/whach/which/

Comment on attachment 8858480 [details] Bug 1313977 - Don't round fractional mouse coordinates up, because doing so might push them outside the window. https://reviewboard.mozilla.org/r/130446/#review133160 > nit: s/whach/which/ thanks for catching that

Pushed by mstange@themasta.com: https://hg.mozilla.org/integration/autoland/rev/eb127a1c43c5 Don't round fractional mouse coordinates up, because doing so might push them outside the window. r=kats

Thanks for fixing this! Please request Aurora/ESR52 approval on this when you get a chance.

Comment on attachment 8858480 [details] Bug 1313977 - Don't round fractional mouse coordinates up, because doing so might push them outside the window. Approval Request Comment [Feature/Bug causing the regression]: starting with Mac OS 10.11, the system sends mouse events with fractional coordinates [User impact if declined]: scrolling annoyance [Is this code covered by automated tests?]: no [Has the fix been verified in Nightly?]: yes [Needs manual test from QE? If yes, steps to reproduce]: no [List of other uplifts needed for the feature/fix]: none [Is the change risky?]: no [Why is the change risky/not risky?]: small targeted fix [String changes made/needed]: none [Approval Request Comment] If this is not a sec:{high,crit} bug, please state case for ESR consideration: low-risk targeted fix for an annoying UI interaction issue User impact if declined: users can't scroll if the mouse is at the very edge of the screen Fix Landed on Version: 55 Risk to taking this patch (and alternatives if risky): very low String or UUID changes made by this patch: none

Comment on attachment 8858480 [details] Bug 1313977 - Don't round fractional mouse coordinates up, because doing so might push them outside the window. Fix a scrolling issue in Mac. Aurora54+. Hi :asimonca, Can you help check if the issue is fixed in the latest nightly?

Hi, This is fixed in the latest Nightly using macOS Sierra 10.12.3.

Also fixed in Beta 54b1 on MacOs El Capitan 10.11.6.

Comment on attachment 8858480 [details] Bug 1313977 - Don't round fractional mouse coordinates up, because doing so might push them outside the window. This problem has been around for a few releases but it seems is worse since Sierra release, fix has stabilized in 54 for a month, ESR52.2+

Fixed in ESR 52.2.0 on MacOS Sierra 10.12.5