1434110 - Tabs don't reach the top of the screen when a browser window is open on an external display

Status: RESOLVED DUPLICATE of bug 1302168

(Firefox :: Tabbed Browser, defect)

Description

[Asa Dotzler [:asa]]

Tabs don't reach the top of the screen when a browser window is open on an external display. Tested with latest nightly build on Windows 10. Reported in the wild on release 58. 

Steps to reproduce:
1. Launch Firefox on Windows 10.
2. Maximize a browser window on external monitor
3. Move your mouse to the top edge of the screen and click to select a tab

Results: 
Tab is not selected. There's some empty space above the tap that breaks the Fitts's law benefits of having tabs on top. 

Expected results:
The tab is selected because it (or its clickable area) extends to the top of the screen. 

Tested on a Windows 10 Surface Book with 3000x2000 resolution and an external screen with 2560x1600 resolution. See also bug 1322854 which specifically talks about 4K screens but reports a similar issue.

Comment 1

[Chris Peterson [:cpeterson]]

I filed bug 1302168 in 2016 about this problem with my external monitor. It is problem with Firefox's handling of Windows' display scaling. I could make the problem go away on my monitor by changing Windows' display scaling to 225%.