User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0 Build ID: 20170217004020 Steps to reproduce: 1. open firefox on secondary screen 2. move window to primary screen i'm using firefox on a razer blade 2016 with an "intel HD graphics 530", have a secondary dedicated graphics card nvidia GTX 1060 (which is not used per default for firefox). i think it's related to native scaling on win10. if i set the secondary screen to 125% i can see when the scaling of ff happens, and before the scale changes the window is rendered normally, but afterwards it goes black. Actual results: window renders normally on secondary screen, but is black with light title bar on primary screen. even if half of the window is on primary and the other half on secondary, the primary-half is rendered black. Expected results: the firefox window should be rendered normally on both screens

Could you give more details about your setup: 1) type about:support in the location bar and copy the section "graphics" 2) for each monitor, could you specifify the HiDPI and resolution.

the graphics part: --- Allgemeine Merkmale Compositing Direct3D 11 Asynchrones Wischen und Zoomen Mausrad-Eingabe aktiviert; Berührungs-Eingabe aktiviert WebGL-Renderer Google Inc. -- ANGLE (NVIDIA GeForce GTX 1060 Direct3D11 vs_5_0 ps_5_0) WebGL2-Renderer Google Inc. -- ANGLE (NVIDIA GeForce GTX 1060 Direct3D11 vs_5_0 ps_5_0) Audio-Back-End wasapi Direct2D true DirectWrite true (10.0.14393.351) GPU 1 Aktiv Ja Beschreibung NVIDIA GeForce GTX 1060 Herstellerkennung 0x10de Gerätekennung 0x1c20 Treiber-Version 21.21.13.7866 Treiber-Datum 2-9-2017 Treiber C:\Windows\System32\DriverStore\FileRepository\nvrzi.inf_amd64_99ff9e0a63b90d4d\nvd3dumx,C:\Windows\System32\DriverStore\FileRepository\nvrzi.inf_amd64_99ff9e0a63b90d4d\nvwgf2umx,C:\Windows\System32\DriverStore\FileRepository\nvrzi.inf_amd64_99ff9e0a63b90d4d\nvwgf2umx,C:\Windows\System32\DriverStore\FileRepository\nvrzi.inf_amd64_99ff9e0a63b90d4d\nvwgf2umx C:\Windows\System32\DriverStore\FileRepository\nvrzi.inf_amd64_99ff9e0a63b90d4d\nvd3dum,C:\Windows\System32\DriverStore\FileRepository\nvrzi.inf_amd64_99ff9e0a63b90d4d\nvwgf2um,C:\Windows\System32\DriverStore\FileRepository\nvrzi.inf_amd64_99ff9e0a63b90d4d\nvwgf2um,C:\Windows\System32\DriverStore\FileRepository\nvrzi.inf_amd64_99ff9e0a63b90d4d\nvwgf2um Subsys-ID 674f1a58 RAM 6144 GPU 2 Aktiv Nein Beschreibung Intel(R) HD Graphics 530 Herstellerkennung 0x8086 Gerätekennung 0x191b Treiber-Version 21.20.16.4534 Treiber-Datum 10-7-2016 Treiber igdumdim64 igd10iumd64 igd10iumd64 igd12umd64 igdumdim32 igd10iumd32 igd10iumd32 igd12umd32 Subsys-ID 0000000c RAM Unknown Weitere Informationen AzureCanvasAccelerated 0 AzureCanvasBackend Direct2D 1.1 AzureCanvasBackend (UI Process) skia AzureContentBackend Direct2D 1.1 AzureContentBackend (UI Process) skia AzureFallbackCanvasBackend (UI Process) cairo GPUProcessPid 12296 GPUProcess Entscheidungsprotokoll D3D9_COMPOSITING disabled by default: Disabled by default --- looks like it's really running on the nvidia card. primary monitor: 2560x1080 @ 96dpi secondary monitor: 1920x1080 @ 157dpi i also found out that if i use aero snap (win+cursor) to move the working firefox window from the secondary to the primary window, the problem doesn't occur

Gernot, did this problem exist on earlier versions of firefox? Or was it that your set up changed rather than firefox? Could you confirm whether disabling hardware acceleration works around the bug? Thanks.

disabling hardware acceleration is a workaround, the black areas are gone. i currently don't require hardware acceleration so this fixes the issue for me for now. but is this something which is going to be fixed?

Other than the second monitor, this is likely related or the same as bug 1163440, and most of the traffic is there. We do want to fix this.