this happens to all windows without a tabstrip e.g. following javascript:

window.open('chrome://blank', 'blank', 'width=300,height=300');

cannot be closed by double-clicking on the top left of the window.

We are talking about removing that for main chrome windows, but I think if there is a window icon it should be consistent with other Windows window icons. So I will fix this.

Alternative repro is to use

  chrome.exe --app=https://mail.google.com

Notably, if you click *to the left* of the icon (red box in the attached screenshot), the system menu properly activates (and double-click closes the Chrome Window).

In other Windows applications, and Chrome 67 before the recent custom title bar change, clicking in the icon (green box in the attached screenshot) invokes the system menu, and double-click closes the Chrome Window.

> We are talking about removing that for main chrome windows

FWIW, breaking consistency with two decades of Windows behavior would make me sad. 

Deleted: ClickTargets.png 3.4 KB

	ClickTargets.png 3.4 KB View Download

This regression also impacts undocked DevTools windows.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0d969695fcd4ef5a32925f760b909adc891ba90f

commit 0d969695fcd4ef5a32925f760b909adc891ba90f
Author: Bret Sepulveda <bsep@chromium.org>
Date: Fri Apr 13 01:57:28 2018

Fix system menu not appearing when clicking the corner of popup windows.

On Windows the system menu is expected to appear on a single left-click
to the top-left corner of the window, and a double click is expected to
close the window. The Views window icon added by custom titlebar was
intercepting the click and so the WM_NCLBUTTONDOWN message was not
getting DefWindowProc'ed. This patch fixes this by disabling event
handling on that icon, as it isn't supposed to do anything.

Bug:  828429 
Change-Id: I1ee0cfe38707479948b51eed48da83639964a7ae
Reviewed-on: https://chromium-review.googlesource.com/1011544
Reviewed-by: Peter Boström <pbos@chromium.org>
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550472}
[modify] https://crrev.com/0d969695fcd4ef5a32925f760b909adc891ba90f/chrome/browser/ui/views/frame/glass_browser_frame_view.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0d969695fcd4ef5a32925f760b909adc891ba90f

commit 0d969695fcd4ef5a32925f760b909adc891ba90f
Author: Bret Sepulveda <bsep@chromium.org>
Date: Fri Apr 13 01:57:28 2018

Fix system menu not appearing when clicking the corner of popup windows.

On Windows the system menu is expected to appear on a single left-click
to the top-left corner of the window, and a double click is expected to
close the window. The Views window icon added by custom titlebar was
intercepting the click and so the WM_NCLBUTTONDOWN message was not
getting DefWindowProc'ed. This patch fixes this by disabling event
handling on that icon, as it isn't supposed to do anything.

Bug:  828429 
Change-Id: I1ee0cfe38707479948b51eed48da83639964a7ae
Reviewed-on: https://chromium-review.googlesource.com/1011544
Reviewed-by: Peter Boström <pbos@chromium.org>
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550472}
[modify] https://crrev.com/0d969695fcd4ef5a32925f760b909adc891ba90f/chrome/browser/ui/views/frame/glass_browser_frame_view.cc

 Issue 852245  has been merged into this issue.