Problems in Windows 10 When Using Unscaled Output at 4K Resolution

[reynolds087]

Hi,

I have been using VirtualBox for a year or so now on a dual monitor Windows 10 Host with my second monitor being a 4K TV. Normally I use the unscaled output and it works just fine, but since the last VirtualBox update, one of my guests has started to have critical issues when running it unscaled. I have had to set the scaling to 150% or above in order to use it. The symptoms that occur are application windows and the start menu freezing, or "trailing". Sometimes the screen won't refresh for several minutes or even not at all in extreme cases. Scrolling through lists or other basic animations are no longer working, or they work erratically. The mouse will randomly disappear if it's over the guest window, and only show in the host. Basically the system has become unusable at full resolution. Both my host, as well as my guest are running the latest build of Windows 10 x64 1903 with all updates installed. Hardware is i7 8700K CPU, and a GTX 1080 TI graphics card. 2D acceleration is enabled, 3D acceleration disabled, and video memory is set to 256 MB. 3 cores and 6144 MB RAM are allocated to the guest OS. Utlization is staying below 50% in the guest, and below 20% in the Host.

[reynolds087]

Bump

[socratis]

HiDPI support was added for WinHosts with 6.0.0 and there are some issues.

I've been using it on OSX hosts for a couple of years and what I do is to go to the VirtualBox Preferences » Display » Scale Factor, and set that to 200%. I do not touch the per VM Scale Factor, just the global one. And in my guests (like Windows), I do not touch a single setting. All is working as expected.