1389819 - Web Extension DPI scaling of BrowserAction Popups

Status: RESOLVED DUPLICATE of bug 1387340

(WebExtensions :: Frontend, defect)

Description

[ober.sebastian]

Attachment: webext-browseraction-scaling.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0
Build ID: 20170812100345

Steps to reproduce:

Using the latest Firefox Nightly onWindows 10 64bit with an highDPI laptop with an external monitor, and scaling done by windows setting:
- Main screen 2560x1440, scaling 175%
- External monitor 1680x1050, scaling 100%

I opened a web extension popup (for example ublock origin, umatrix, or my own web extension) when the browser window is on the laptop screen, moved the browser window to the other screen and opened it there.


Actual results:

While on the main screen, the popup looks normal, on the other (secondary) monitor, the content of the popup is scaled too much.
The device pixel ratio according to window.devicePixelRatio is about 1.76 on both screens. The attached screenshot illustrates the problem on the secondary screen.
This happens despite regardless of relative css widths, absolute pixel widths or em widths.


Expected results:

The popup displays the same (or similar) on both screens instead of being cut off.