1397931 - page content janks during resizing when moving Firefox windows between screens

Status: NEW

(Core :: Layout, enhancement, P3)

Description

[Asa Dotzler [:asa]]

When I move a browser window between my retina macbook or my surface book and an external screen the content resizes to really small or really large before settling on the right size. 

When I move a window to the external screen the content gets really big and then sizes correctly. When I move the window from the external screen to the laptop screen the content gets really tiny before resizing to the proper size. 

Ideally we'd skip that really wrong size for the content and go right to the correct size. 

Tested on Mac and Windows on today's nightly build. 

Windows laptop: Surface Book with 3000x2000 screen at default 200% scale
Mac laptop: MBP with retina screen default scaled to look like 1280x800
External screen: 2560x1600 at 100% scale