Can you run xev on the host and see what events it records for Win+Click? You'll need to click on the xev window to avoid defocusing it--try not to move the mouse too much or the output will be very spammy.

MotionNotify event, serial 37, synthetic NO, window 0x5000001,
    root 0x16c, subw 0x5000002, time 605685877, (44,38), root:(147,156),
    state 0x10, is_hint 0, same_screen YES

MotionNotify event, serial 37, synthetic NO, window 0x5000001,
    root 0x16c, subw 0x5000002, time 605686004, (44,39), root:(147,157),
    state 0x10, is_hint 0, same_screen YES

KeyPress event, serial 37, synthetic NO, window 0x5000001,
    root 0x16c, subw 0x5000002, time 605687701, (44,39), root:(147,157),
    state 0x10, keycode 133 (keysym 0xffeb, Super_L), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

MotionNotify event, serial 37, synthetic NO, window 0x5000001,
    root 0x16c, subw 0x5000002, time 605687702, (44,39), root:(147,157),
    state 0x50, is_hint 0, same_screen YES

LeaveNotify event, serial 37, synthetic NO, window 0x5000001,
    root 0x16c, subw 0x5000002, time 605687702, (44,39), root:(147,157),
    mode NotifyGrab, detail NotifyVirtual, same_screen YES,
    focus YES, state 336

FocusOut event, serial 37, synthetic NO, window 0x5000001,
    mode NotifyGrab, detail NotifyAncestor

EnterNotify event, serial 37, synthetic NO, window 0x5000001,
    root 0x16c, subw 0x5000002, time 605687793, (44,39), root:(147,157),
    mode NotifyUngrab, detail NotifyVirtual, same_screen YES,
    focus YES, state 80

KeymapNotify event, serial 37, synthetic NO, window 0x0,
    keys:  108 0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   
           32  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   

FocusIn event, serial 37, synthetic NO, window 0x5000001,
    mode NotifyUngrab, detail NotifyAncestor

KeymapNotify event, serial 37, synthetic NO, window 0x0,
    keys:  1   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   
           32  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   

KeyRelease event, serial 37, synthetic NO, window 0x5000001,
    root 0x16c, subw 0x5000002, time 605688634, (44,39), root:(147,157),
    state 0x50, keycode 133 (keysym 0xffeb, Super_L), same_screen YES,
    XLookupString gives 0 bytes: 
    XFilterEvent returns: False

LeaveNotify event, serial 37, synthetic NO, window 0x5000001,
    root 0x16c, subw 0x5000002, time 605691038, (456,91), root:(559,209),
    mode NotifyNormal, detail NotifyNonlinearVirtual, same_screen YES,
    focus YES, state 16

FocusOut event, serial 37, synthetic NO, window 0x5000001,
    mode NotifyNormal, detail NotifyNonlinear

I don't necessarily think it's a chromoting issue, unless chromoting was specifically suppressing this behavior of Chrome OS in the past and is now failing to do so.

Sorry for the delay getting back to you. Can you clarify whether you're talking about the client-side (ChromeOS) search window, or the host-side (Unity) search window. If it's the former, then can you confirm whether or not the same thing happens if you so Win+Click outside of Chromoting?

This is the client-side window. Key-up on Win will pop up the Chrome OS search window now, even if I clicked in the mean time. (I am almost certain this is new behavior.)

And this happens outside of Chromoting as well.

Sounds like an issue with ChromeOS in general. I'm going to remove the Chromoting tag, which might help with triaging.

@afakhry could we avoid triggering the launcher if a click occurs between windows keydown and keyup?

ping

this still gets me every time

I'm not going to get to this any time soon, weidongg@ please take a look. Thanks!

For convenience:
Linux->ChromeOS: client is Linux while host is Chrome OS.
ChromeOS->Linux: client is Chrome OS while host is Linux.

Hey, when I reverse the chromoting from ChromeOS->Linux to Linux->ChromeOS. I press WIN in client, the linux launcher pops up. When I press mouse button between press WIN and release WIN, the Linux launcher still pops up. 

This is the similar behavior when you press Search key in ChromeOS->Linux chromoting, right? It seems that this is not Chrome OS specific problem?

I'm not sure what your Linux environment looks like, but Win-Down, click, Win-Up does not pop up anything on my setup. Win alone will trigger an action.

Sorry for the late reply. +tbuckley@ could you be more specific about the expected behavior here? Should we avoid app launcher when any touch and mouse event occurs during the search key clicks, or just the mouse click?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/272d1bb23336c996a82630c0711c19d94a480ad0

commit 272d1bb23336c996a82630c0711c19d94a480ad0
Author: weidongg <weidongg@chromium.org>
Date: Sat Jul 08 00:01:09 2017

Avoid toggling app list if interrupted by mouse

If mouse press/release occurs between search key down and up, avoid
toggling app list. This is helpful when user is chromoting from chromeos
to other system which uses 'Win+Click' as a gesture.

BUG= 665897 
TEST=
ash_unittests --gtest_filter=
'AcceleratorControllerTest.GlobalAcceleratorsToggleAppList'
ash_unittests --gtest_filter=
'AcceleratorFilterTest.ToggleAppListInterruptedByMouseEvent'

Review-Url: https://codereview.chromium.org/2923723002
Cr-Commit-Position: refs/heads/master@{#485107}

[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ash/accelerators/accelerator_controller.cc
[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ash/accelerators/accelerator_controller_unittest.cc
[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ash/accelerators/accelerator_filter_unittest.cc
[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ui/base/accelerators/accelerator.cc
[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ui/base/accelerators/accelerator.h
[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ui/base/accelerators/accelerator_history.cc
[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ui/base/accelerators/accelerator_history.h
[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ui/wm/core/accelerator_filter.cc
[modify] https://crrev.com/272d1bb23336c996a82630c0711c19d94a480ad0/ui/wm/core/accelerator_filter.h