This looks like issue with 3 monitor setup as in-house team not having the setup,hence adding the respective label for it to triage further.

Thank You!

Thank you Mickael for letting us know the issue.
Maybe I can setup the configuration and try to reproduce it.

Would you please let us know how monitors are connected? Maybe Screen 1 is the internal monitor of the laptop; Screen 2 and Screen 3 connect to the dock station.

And is it possible to share the content on the screen even the thumbnail is incorrect?

The following revision refers to this bug:
  https://webrtc.googlesource.com/src.git/+/a7567a94811f8bf75ba833f87b967166506a6292

commit a7567a94811f8bf75ba833f87b967166506a6292
Author: Zijie He <zijiehe@google.com>
Date: Fri Sep 15 18:56:26 2017

Implement DesktopCapturerWrapper and CaptureResultDesktopCapturerWrapper

Wrapper pattern is widely used in DesktopCapturer implementations. So this
change adds DesktopCapturerWrapper and CaptureResultDesktopCapturerWrapper as
the base classes of other wrappers. Implementing a new wrapper should become
easy, the implementation does not need to care about the uninteresting
overrides.

Bug:  chromium:764258 
Change-Id: If91c1b5e778805906f7f77854ea5600aa61bf64a
Reviewed-on: https://webrtc-review.googlesource.com/1420
Commit-Queue: Zijie He <zijiehe@google.com>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#19868}
[modify] https://crrev.com/a7567a94811f8bf75ba833f87b967166506a6292/modules/desktop_capture/BUILD.gn
[add] https://crrev.com/a7567a94811f8bf75ba833f87b967166506a6292/modules/desktop_capture/capture_result_desktop_capturer_wrapper.cc
[add] https://crrev.com/a7567a94811f8bf75ba833f87b967166506a6292/modules/desktop_capture/capture_result_desktop_capturer_wrapper.h
[add] https://crrev.com/a7567a94811f8bf75ba833f87b967166506a6292/modules/desktop_capture/desktop_capturer_wrapper.cc
[add] https://crrev.com/a7567a94811f8bf75ba833f87b967166506a6292/modules/desktop_capture/desktop_capturer_wrapper.h

Hi zijiehe,
Sorry for the late reply, the screen indeed is one built in laptop monitor and two external monitors connected by a dock station.
The problem occurs on the build in monitor and one external monitor.

About the second question, it's possible to record the duplicated screen, but the mouse pointer doesn't appears. 

I can successfully reproduce this issue on my device:
  - Thinkpad X1 Carbon 5th Gen
  - Thinkpad USB 3.0 Pro Dock
The issue happens when two or more external monitors connect to the system, no matter how the monitors connect. I.e. two to the dock or one to the dock, one to the laptop.

I cannot find a root cause so far.

For the disappearance of mouse pointer, it has been fixed in M62.

The following revision refers to this bug:
  https://webrtc.googlesource.com/src.git/+/8f1b93c1044d528879141d7e1712df9bf5ad7951

commit 8f1b93c1044d528879141d7e1712df9bf5ad7951
Author: Zijie He <zijiehe@google.com>
Date: Tue Sep 26 02:02:42 2017

Add more logs in DX capturer

This is a trivial change to add more logs in DX capturer components for
debugging purpose.

Bug:  chromium:764258 
Change-Id: I406127d838a522f0226720434e840c7163b4719d
Reviewed-on: https://webrtc-review.googlesource.com/3541
Commit-Queue: Zijie He <zijiehe@chromium.org>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#19960}
[modify] https://crrev.com/8f1b93c1044d528879141d7e1712df9bf5ad7951/modules/desktop_capture/win/dxgi_adapter_duplicator.cc
[modify] https://crrev.com/8f1b93c1044d528879141d7e1712df9bf5ad7951/modules/desktop_capture/win/dxgi_duplicator_controller.cc
[modify] https://crrev.com/8f1b93c1044d528879141d7e1712df9bf5ad7951/modules/desktop_capture/win/dxgi_duplicator_controller.h
[modify] https://crrev.com/8f1b93c1044d528879141d7e1712df9bf5ad7951/modules/desktop_capture/win/screen_capturer_win_directx.cc

I ordered a dock for my Thinkpad and will see if I can have any luck or not.

I reproduced the issue with this dock station.
https://www.google.com/search?q=Lenovo+USB+3.0+Pro+Docking+station(+40A70045US+)In+The+Factory+Sealed+Lenovo+USA+Retail+Packaging&oq=Lenovo+USB+3.0+Pro+Docking+station(+40A70045US+)In+The+Factory+Sealed+Lenovo+USA+Retail+Packaging&aqs=chrome..69i57j69i60j69i64&sourceid=chrome&ie=UTF-8

Thanks zijiehe@.
I ordered Lenovo Thinkpad Thunderbolt 3 Dock, which is specially for my X1 Yoga V2, from our own inventory. If it doesn't work, I'll try the USB Dock. Then maybe we can know if this is a common issue or specific issue :)

 Issue 796078  has been merged into this issue.

I can't reproduce this problem with X1 Yoga V2(Win10) + Thunderbolt 3 Dock. See the attached screenshot.

May it be a USB3.0 dock specific issue? 

Deleted: screen-shot.PNG 83.1 KB

	screen-shot.PNG 83.1 KB View Download

I agree. On my machine, the behavior of the USB 3.0 dock station is pretty unstable. One thumbnail of the three may randomly switch between two monitors.

P.S. The hardware encoder (H264) immediately stops working after the third monitor is connected. This fact also gives me some level of confidence to indicate the hardware or driver limitation.

Tried to connect 3 monitors to my windows desktop and can't see the problem.
So it should be a HW/driver specific issue in OS.
Close it for now. 

I've reproduced and captured the bug in the attached video. My actions are described with the following time stamps:
4: Open the screen share dialog, demonstrating function as intended.
9: Double press Win-D, minimizing and maximizing all windows.
14: "Dialog screen 3" is now swapping between "physical screens 1 and 2".
23: Moving a few windows results in "dialog screen 3" swapping between "physical screens 2 and 3", eventually returning to only 3, as intended.
35: Minimizing all windows on "physical screen 3", resulting in "dialog screen 3" returning to "physical screen 1 and 2".
47: Minimizing all windows on "physical screen 2", resulting "all dialog screens" exclusively showing "physical screen 1".
60: Demonstrating that all windows has disappeared from application window selection.

Somehow the bug could not be reproduced while screen capturing, so I had to use an external capture device. As such, I believe the windows API to be at fault, but I also think it's possible to fix. I've had similar bugs in another Win32/GDI/BitBlt capture application which was resolved by disposing invalid (usable, but unpredictable) HDC handles and changing the method of detecting visible windows.

Deleted: duplicate_previews.mp4 997 KB

	duplicate_previews.mp4 997 KB View Download

Thank you for sharing us the information. Are you using the dock-station to connect to the third physical monitor?

I have not reproduce the bug with GDI based capturer, but this issue happens with DirectX based capturer only. It works well by using a fairly high performance video adapter, but fails on the dock-station. So we believe this is a platform / driver specific issue.

I'm working with skadberg@ on issue792492, screen capture flickering on multi-monitors case.

His test setup is 3-monitor setup using a nVidia GeForce GTX 660 Ti.
Mine is 3-monitor setup using a nVidia Quadro K2200.

I'm just too lucky(or unlucky) to not being able to reproduce this problem, with both of my setups.
If there is more information on how to do to handle this situation, I'd love to add it into chromium. Maybe only use GDI capturer for picker thumbnails?