Given that this only happens in the specific circumstance of using Synergy to forward mouse and keyboard events it seems highly likely that there's some issue with the event forwarding and not any bug in Chrome itself.

chihochun: Can you please try doing the same repro steps but in some other non-Chrome UI to see if a similar issue occurs?

Yes, I have tested in different places and confirmed it only happens in
chrome. I also confirm that its a regression since the chrome UI has
changed. The old UI did not have this issue.

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

chihochun@ Thanks for the issue.

Synergy setup is not available at TE end to test and confirm this issue.
Hence adding 'TE-NeedsTriageHelp' label and requesting the appropriate team to look into the issue and help in further triaging.

Thanks..

mac triage: lgrey@, can you take a peek at this?

Thanks for taking care of this :)

For additional information, this is what synergy printed when cmd button was pressed and released.

[2018-09-26T17:26:27] DEBUG1: new mask: 0x2000
[2018-09-26T17:26:27] DEBUG1: event: KeyPress code=133, state=0x0010
[2018-09-26T17:26:27] DEBUG1: onKeyDown id=61419 mask=0x2000 button=0x0085
[2018-09-26T17:26:27] DEBUG1: send key down to "chihochun-macbookpro33.roam.corp.google.com" id=61419, mask=0x2000, button=0x0085
[2018-09-26T17:26:28] DEBUG1: new mask: 0x2010
[2018-09-26T17:26:28] DEBUG1: event: KeyRelease code=133, state=0x0050
[2018-09-26T17:26:28] DEBUG1: onKeyUp id=61419 mask=0x2010 button=0x0085
[2018-09-26T17:26:28] DEBUG1: send key up to "chihochun-macbookpro33.roam.corp.google.com" id=61419, mask=0x2010, button=0x0085

Thanks for looking into this. I also get the same output (and that it's driving me nuts :) ).

Does it appear to select all right before? I'm seeing something similar in  Issue 889618  (and hoping it's the same root cause because it's a much easier repro :))

 Issue 891509  has been merged into this issue.

I added another bug(Issue 891760) which can potentially be related.

Anyone affected by this: could you try the latest Canary (71.0.3570.0 ) and see if it's fixed?

How do I get the latest Canary?

https://www.google.com/chrome/canary/

I verified that the issue is fixed on latest canary

Great, thanks!

What is the release schedule of the version with this fix included? (or at least within Google). Just want to know when to stop using the canary version.

M71 will hit stable around the first week of December and beta towards the end of this month.

Thanks!