Dual Display / Monitor is flashing on focus change

[TBay]

Hi everybody,

I am using a Lenovo T540p Laptop with 2 additional displays. VirtualBox Version is 5.1.18 with Guest Additions installed. Host OS is W10 1607 64bit. Guest OS is the same. Both fully patched.
Host is configured to use the internal display. Guest is configured to use the two external displays in full screen mode.

The issue is, that when I change the focus from one external display to the other one by clicking into the screen, both external displays shortly turn black. If I switch rapidly from one to another and back, they are even flashing not only once but often so it could be used as a strobe at the next party.

I've tested the same VM on another Lenovo Notebook (T520) with the same host OS and the same VirtualBox version installed and there is no issue.

Have you got a clue how to get this issue fixed ?


Thanks in advance
Thomas

[TBay]

OK,

seems that I found something. On the system with the issue the 2D video acceleration was off. After turning it on the screens does not turn black anymore. But it is still to notice, that window frames are flickering a little. But this should be no problem anymore.

Another hint could be,that the T520 Laptop has got an Intel Graphics 3000 adapter only, while the T540p has got an Intel Graphics 4000 and a Nvidia NVS5400 too and I configured VirtualBox to use Nvidia now.

But if you got other hints why there is this flickering for example, let me know.