Windows 10 latest feature update 1809 breaks dual screen (#18016)

[Chris I]

Posted on #18016, but will post here as well:

I'm able to reproduce this as well with a Windows 10 1809 dual-display guest.

Host is Fedora 29, with 2x 1920x1080 monitors (same model), so there are no per-display DPI changes involved. However, my left monitor is Portrait, while the right monitor is Landscape.

Basically, if you take screens 1 & 2 from Venty's diagram, that's approximately correct for my display arrangement. However, the actual mouse mappings to the guest are different than illustrated.

[Chris I]

Having some screen recording problems, but I managed to record my screen: https://www.youtube.com/watch?v=jbxs34jFAG8 (Note: I can't post URLs here)

First 25 seconds is single-display guest. Note the mouse positioning is good.

Second 25 seconds is dual-display guest. Clicking on the second display, all mouse input is offset at a scaled rate. Note that at 40 seconds, the mouse is in the bottom-right of display #2, while the click/drag box is at the top of display #1.

Not shown in the video, but in with a single guest display, the mouse is correct on either monitor, or even when split between both monitors.

[Croatian]

Also, did you try the latest 5.2.x Test builds? Or even the Development Snapshots? If you want to use the latest version for your host/guests, you should also consider doing the same for VirtualBox. That means test builds, and even those are earlier than yesterday's Win10 upgrade.

I did try it on my MacOS VB host with Windows 10 1809 (yesterday's feature update) as a guest. I used the latest developer snapshot, not the test build. The GA and extension pack are also the latest. Still, the same thing occurs no matter what. Adding a separate mouse to a USB port and adding that mouse using a USB filter for the guest works okay, although buggy at times due to the invisible mouse pointer. Also, these screens are not at very high DPI, they are both quite regular. One thing I did notice is that the mouse behaves in a way that it follows the pixel mapping/geometry of the smaller of the two screens, using its geometry as a template for the mouse pointer position.

[socratis]

I observed the same issue on my OSX 10.11.6. Here's what (I think) I figured out. I don't have fancy graphics ( ), I prefer ASCII-art:

+-------------------+                                      +-------------------------------+
|                   |                                      |                               |
|                   |+----------+                          |                               |
|                   |           |                          |                               |
|     1280x1024     |  800x600  |   VirtualBox thinks ->   |           2080x1024           |
|                   |           |                          |                               |
|                   |+----------+                          |                               |
|                   |                                      |                               |
+-------------------+                                      +-------------------------------+

What happens is that the mouse "thinks" that is has a working area of (1280+800)x1024=2080x1024. And it "scales" its movements accordingly. So, when at the most left-hand-side, you are alright. The more you move to the right, the movement is scaled by 2080/1280=1.625. So, moving 200 px to the right the cursor, actually moves the underlying active-click-coordinates by 325 px. Oops...

[Dunum]

I have the same problem. Single screen ok - dual screen not!

However, I have also lost my shared folder following the 1809 Windows update. The VirtualBox tray icon shows it to be present - but it does not show up in the "My Computer" folder nor is it accessible via a "Command Prompt". Anybody else seen this?

Not sure if anything else has gone wrong.

[Uzwane]

I think you need to re-install VirtualBox Guest Additions on the guest.
It might bring back the shared folders.

[Chris I]

What happens is that the mouse "thinks" that is has a working area of (1280+800)x1024=2080x1024. And it "scales" its movements accordingly.

I saw similar, but slightly different results.

Clicking in the left display mapped 1:1 but to the right display (not shown in my video). Clicking on the right display did appear to scale (in my video) like you describe. It eventually wrapped back around to the left display.

[Dunum]

re. Loss of Shared Folders...
Thanks Uzwane. I re-installed Guest Additions and shared folders now ok.
Just need to get the dual screen problem sorted now.

[nukeme1]

I have 3 identical physical screens in 1080p, all in landscape mode (basically 3 identical screens side by side). My virtual machine is setup to use the 2nd and 3rd physical screen and has the GA reinstalled post-update. The clicking is still messed up location-wise even though all the screens have the same resolution/layout/physical model so there definitely is something that has changed in 1809 that does not play well with the GA mouse integration. Does anyone have any idea what is the cause/possible solution/ETA to a fix?

[Croatian]

As yet another workaround, you can enable mouse trails in Windows 10. You'll end up with two mouse pointers that mimic each other's moves. The mouse pointer with trails becomes your actual Windows 10 mouse and the one without trails acts like your host OS mouse. It's not pretty, but it works (if you can put up with the trails). You can enable mouse trails under mouse properties in Windows 10 settings (gear icon).

Annotation.png (25.91 KiB) Viewed 6297 times

[nukeme1]

Welp, based on this workaround, we can easily see what is happening, the movement on a single monitor of the host (the main monitor I guess) is scaled to the multiple monitors in the guest, basically, if I move across the distance of 1 monitor host-wise, this gets translated to 2 monitors in the 2-monitor guest, I imagine that n-monitor guests also scale accordingly and must become nigh unusable since a small move from the mouse basically equates to n times the same movement in the guest. I really hope this gets sorted out soon because it is quite an annoyance. Thanks for the workaround though, although ugly, it is a little easier to use than disabling mouse integration entirely.

[Squonk1]

no change in 5.2.20

[nukeme1]

No change in 5.2.22-126460

[...don]

Same problem. ASUS laptop Linux host running 5.2.22. Two ASUS monitors with "Extended" displays both at 1920x1080. Problem occured after Windows hosts upgraded to October 1809.

[socratis]

Can you try with the 6.0.0beta? I think it's fixed there.

Edit: I meant the Development Builds, sorry about any confusion.