1275070 - [OSX][4K] Black bar covers tab bar when started with window width above 2049px

Status: RESOLVED WORKSFORME

(Core :: Widget: Cocoa, defect, P4)

Description

[Adrian Göransson]

Attachment: problem.png

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:48.0) Gecko/20100101 Firefox/48.0
Build ID: 20160523004008

Steps to reproduce:

Start Firefox with a window size that exceeds 2049/3073,5 (retina 1.5x mode) pixels in width.

Display: Dell P2715Q, 3840x2160
OSX monitor settings: "Looks like 2560x1440" = 1.5x mode.


Actual results:

Black bar covers the tab bar. See attached image `problem.png`. 

Resizing the window down below 2049/3073,5 makes the black bar disappear. The black bar then stays gone even if the window width resized back to its original size.


Expected results:

No black bars should be present.

Comment 1

[Adrian Göransson]

This has previously been discussed in Bug 910144 but it was not the same issue so this issue was filed instead.

Comment 2

[Adrian Göransson]

Attachment: 4k_problem_fix.mov

Added a screen recording showing the bug and how to get out of it. The fix temporary as it only affects current window.

Comment 3

[Matthew N. [:MattN]]

Thank for filing. I guess this has something to do with drawing in the titlebar. Can you confirm that the problem goes away if you turn on the system titlebar from Customize mode? Just toggle the "Title Bar" button in the bottom left corner.

https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars#w_turn-on-the-title-bar-or-bookmarks-toolbar

Comment 4

[Adrian Göransson]

Thanks for the reply Matthew,

Turning on the system title bar makes the black bar go away for the current window. Opening a new window presents the problem again, only this time it's not as annoying since it only covers the system title bar instead of Firefox's UI.

Should be noted that toggling the system title bar doesn't fix the problem. If I were to toggle back to the original it would have the black bar still.

The resizing trick still works, with or without system title bar.

Comment 5

[Adrian Göransson]

Hey! Since I updated to Firefox 50 this issue seems to be gone.

Comment 6

[Matthew N. [:MattN]]

Thanks Adrian, I guess I will mark this as "works for me" then. If you're interested in knowing what bug actually fixed this you could use mozregression[1] to bisect the Nightly builds.

[1] https://mozilla.github.io/mozregression/