1202056 - Rendering problem when moving window between monitors on OS X

Status: NEW

(Core :: XUL, defect)

Description

[edtecot]

Attachment: Screen Shot 2015-09-04 at 3.49.03 PM.png

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:40.0) Gecko/20100101 Firefox/40.0
Build ID: 20150826023504

Steps to reproduce:

1) Open any web page in Firefox (for example, https://bugzilla.mozilla.org/enter_bug.cgi#h=bugForm|Firefox)
2) Drag the window to another monitor.


Actual results:

Contents of window is all messed up.
Sometimes it just shifts to the right, sometimes it gets scaled incorrectly.


Expected results:

Contents of the window should remain the same as before.

See attachment for one example.

Comment 1

[edtecot]

One thing I forgot to mention - resizing the window corrects the problem.

Comment 2

[ryanblazecka]

I am also having this problem; the screenshot from edtecot is the kind of stuff I see too. I think it's related to the difference between the Retina display on my laptop, and the regular 1600x1200 display I have hooked up to it. It seems that when I move Firefox from one to the other, the page contents aren't rescaled properly for the new resolution. Resizing the window once it's on the new display does fix it, although if I'm in full screen mode, this means returning to windowed mode and back.

When moving the window from the hiDPI display to the loDPI display, the window contents will be rendered rendered too small; everything is crammed into the upper-left ~60% of the Firefox window. The scroll bars are over there too, not at the right and bottom edge. It's as if Firefox thinks it has a much smaller display than it does, and isn't making use of all of it.

Moving the window from the loDPI display to the hiDPI display gives the inverse; Firefox is using the whole window, but the page contents are wider than the window. I need to use the horizontal scroll bars to see the full width of the page.

Resizing the window fixes both cases.

This has been happening for several months at least.

Comment 3

[Justin [:JW_SoftvisionQA]]

Hello all, 

Can you both try to reproduce on the newest build: 20151116030208?

Thank you,

Justin

Comment 4

[ryanblazecka]

Is there an easy way to get that build? I'm just running the regular stable release, and it's not clear where I can find a build that contains the change you're wanting us to test.

Also, will said build interact in any way with my regular stable installation of Firefox?

Comment 5

[Justin [:JW_SoftvisionQA]]

I'm sorry Ryan. Here is the link to the build I was referring to: https://nightly.mozilla.org/ 

Downloading is simple, just click on the Mac download and it will be downloaded. This is the most up-to-date build.

Let me know if you have other questions.

Comment 6

[edtecot]

I tested with Nightly 45.0a1 (2015-11-18).

Now Firefox redraws the viewport twice; once at the incorrect scale and once at the correct scale.  This is an improvement from before, but really not the right approach.

Both Chrome and Safari seem to handle the same situation without any unnecessary redraws.

Comment 7

[Justin [:JW_SoftvisionQA]]

Alright, I will send this up to a developer.

Comment 8

[Carl Alphonce]

I am experiencing a similar problem with Thunderbird after upgrade to 45.0.  Moving any Thunderbird window from Retina display to external monitor (or vice versa) gives rise to problem.  Resizing the window does seem to fix the issue.

Comment 9

[Carl Alphonce]

Attachment: Thunderbird-RetinaToExternal.tiff

Screenshot showing resolution weirdness.

Comment 10

[ryanblazecka]

Woops, sorry for the long delay on testing this one.

So I just tried the nightly build, and compared with the latest stable release (46.0). The behavior between the two is different.

1) This bug is much harder to reproduce in stable now. It used to be trivial to reproduce, and I could do it 100% of the time under many scenarios. Now, it seems I can reproduce it at best 4/10 times, and that's under the sequence of steps I found most likely to cause it, which took awhile to find.

2) I have been unable to reproduce the bug in nightly. Given that I'm not able to reliably reproduce it in stable, I don't think I can say it doesn't happen in nightly, just that I've not been able to cause it yet.

3) In some ways, the behavior of nightly is now worse than in stable. When moving a window between the hiDPI and loDPI displays in stable, if the bug isn't triggered, everything looks nice: the window is just moved to the other display, and the user never sees anything scaled incorrectly. However, if the bug is triggered, you see the poorly-scaled window contents, and a resize is necessary to make it go away. Conversely, in nightly, when you move the window across displays, you see the poorly-scaled contents every time, but it's immediately corrected. So if the bug isn't triggered, the stable behavior is preferrable, but if the bug is triggered, at least nightly will correct it.

4) For the brief window where you can see the poorly-scaled contents in nightly, it actually is the inverse of the incorrect scaling that happens in stable. For example, in stable, when moving the window from the hiDPI display to the loDPI display, if the bug is triggered the window contents will be much smaller than the application window size. However in nightly, for the brief period when you can see the incorrectly-scaled contents, when moving from the hiDPI to the loDPI display the window contents are actually too big for the application window. Not sure why this would be, but figured it might be helpful in figuring out what's going on.

Comment 11

[Wayne Mery (:wsmwk)]

Firefox issue is perhaps a duplicate of bug 1255638


(In reply to c.alphonce from comment #8)
> I am experiencing a similar problem with Thunderbird after upgrade to 45.0. 
> Moving any Thunderbird window from Retina display to external monitor (or
> vice versa) gives rise to problem.  Resizing the window does seem to fix the
> issue.

Your Thunderbird issue is tracked in Bug 1266354.
Trying to get it fixed in 45.1