Same for me - the DL USB monitor is completely garbled in Parallels and native dialogs like the desktop background pref panel. I can't even use it for what does work, since there are freezes/slowdowns and CPU spikes. I'm on a 2012 non-retina MBP, and everything was working perfectly before I made the mistake of upgrading. Unfortunately, I didn't see this issue when searching for upgrade problems beforehand (argh!)

I'm on an old mac and don't have a corporate apple account, so hopefully those on newer machines that do will be able to successfully apply the pressure needed to fix these unnecessary and obviously untested regressions that are being released into production prematurely.

(Conspiracy-minded people may notice this coincides with apple's new anti-laptop ads in their move towards killng off laptops and switching to iOS-only mobile devices. I think macs will finally be obsolete in their eyes as soon as XCode - the software required to develop for iphones and ipads - can actually run on an ipad.)

Hi All,

Strangely enough this issue does not seem to affect all Macs, even if the same model. I have on my desk a mid-2012 MBP retina that shows the issue and one that does not.

So far I've verified the following do not work:
- Word 2016
- PowerPoint 2016 slideshow
- Keynote
- VLC
- Parallels

Screenshots don't show problems, so it's probably not SW renderer and more a later buffer issue. The kind of corruption also suggests that.

We'll continue investigating.

Regards,
Carlo

Apple has responded
 

Engineering has determined that your bug report (31397880) is a duplicate of another issue (26394372) and will be closed.

The open or closed status of the original bug report your issue was duplicated to appears in the yellow "Duplicate of XXXXXXXX" section of the bug reporter user interface. This section appears near the top of the right column's bug detail view just under the bug number, title, state, product and rank.

An example of the duplicate section from the bug reporter user interface with your bug and the duplicate bug info is included below:

31397880 After upgrading to 10.12.4 window content on external monitors is garbled

State: Closed Product:
Rank: No Value
----------------------------------------------------------------------------------------------
Duplicate of 26394372 (Open or Closed; log in to see the actual state)
----------------------------------------------------------------------------------------------

Thank you pmoston,

We have quite a few bugs duplicate of 26394372, it looks like a catchall for rendering issues on virtual screens.

We have found a possible workaround that worked in our lab: resetting the system management controller.
I suspect an inconsistency between GPU settings between SMC and OS at the time of upgrading to 10.12.4.

In any case I'd suggest to try this workaround. The instructions are in https://support.apple.com/en-gb/HT201295

Please let me know if this helps for you, in case we'll publish the workaround in our FAQ.

Kind regards,
Carlo

Seemed to make it a little better, but still have corruption of the some windows...

I was hopeful when I logged in and saw your suggestion Carlo. I reset per the instructions and nothing has changed unfortunately. Still messed up as before. Prior I could have Parallels open in all 3 displays. My laptop and the 2 external monitors. Not an option anymore. Now I'm limited to the original 2 (laptop and the one external which is Thunderbolt to HDMI. I can however run any Mac programs and run Chrome in the 3rd window being powered by Display Link.

Only temporary
 

Hi Carlo,
the fix was only temporary. After about 20 minutes of working the screen was corrupted again. (Parallels on an external monitor in full screen). :(

My console (console.app) is being flooded with messages

standard 09:39:56.206890 +0200 WindowServer No matching context for device (0x7f991b7123b0) - disabling OpenGL

This only happens with the Display Link hub attached. Any connection?
Maybe the others can check if their console also exhibits the same behaviour?
Regards
Philip

Thank you for trying this out.

At the moment the SMC workaround is still working for us so we no longer have any reproduction in our lab: identical systems work well too.
We have uploaded all information to Apple: we have sysdiagnose for all configurations. Our bug ID is 31495935.

The WindowServer error message may be related in some way but it's now new.

pmoston, it would be fantastic to understand in which circumstances the issue comes back if you can see any pattern. We'll keep trying on our side too.

Kind regards,
Carlo

I've found for Parallels, if you go to "Configure" on the virtual machine, select the "Hardware" tab, go to "Graphics", click "Advanced Settings" and turn OFF "3D acceleration", that this seems to resolve issues for Parallels with a DisplayLink device. You can only make this change when the virtual machine is OFF, and you must make this change for each virtual machine.

That said, I would really love to see a fix for VLC, as I tend to have this on the DisplayLink screen.

Disabling "hardware acceleration" in their preferences screen doesn't resolve issues there; I suspect the setting actually doesn't work.

If I had a guess, it would be any application using 3d hardware acceleration are the applications having issues.