Unable to reproduce the issue on Windows using chromium build M54 #54.0.2840.71 .

@benoit-- Could you please try a system restart and fresh chrome profile , if you still face the issue please write us your observations.

Thanks !

Apart from the obvious probability of a multi-display issue, could this be related to the Windows theme used by the OP (with a transparent titlebar)?

@wox@gmail there is no particular theme, this is what you get when you press WinKey + Tab. I showed this view in order to prove that the windows "still exists" somewhere even it is not rendered

@hdodda I managed to get out of this. If I restart OS without any external display pluged-in I managed to get my devtools back. For now it works even if the location of the floating devtools when pressing F12 looks to be more or less random. 

Thanks for the bug report, OP.  I failed to reproduce this on Canary on a Windows 7 desktop with these steps: open DevTools with F12, close DevTools with F12, repeat.  I will try again on a Windows 10 machine later.

In comment #4, you mentioned that you regained control of the DevTools window after an OS restart.  Are you still able to reproduce the missing window behavior?

Here are some things to try, if it's still reproducible:
- When focus is on the invisible, floating DevTools, can you press Ctrl-Shift-D?  Does that re-dock the DevTools window?
- Instead of F12, could you try Right click > Inspect element OR Ctrl-Shift-I OR Ctrl-Shift-J and see if it still occurs?
- Let's say floating DevTools is open and inspecting a "target page".  When DevTools is missing, try going to "chrome://inspect/#pages" in another tab, find the name of the target page and click the "inspect" link underneath.  Does that regain focus on the DevTools window?

Hi, thank you for your feebacks.

Unfortunately I have no precise scenario to reproduce. I do have the situation back with my two Chromes (regular and Canary). They have now both an invisible floating DevTools, I could test.

-when Ctrl + Shit + D -> yes the dev tools comes back as docked. If I try to undock them I would loose them again.

- Right click inspect, Ctrl+Shitf+J(I) opens the dev tools but still as a ghost window (icon in task bar but cannot focus on the window).
-Using the chrome://inspect/#pages methods, no it does not regain the dev tools.

This is definitely linked to multi display. If I restart OS without any external monitor and hit F12 then I regain a visible and working floating dev tools. 

Even if I plug external display HDMI after, I can work with my dev tools.

I discovered that the position of the dev tools window is very weird and they seem to open with random size and positioning. As long as they are visible this is no big deal I can resize them. My main laptop is high DPI display and the external screen is not high resolution. I believe this confuses the window positioning because I usually use my main screen for Chrome tabs and the other for floating dev tools.

The DevTools window position is set to open with some fixed integers, which I assume are the distance from the top-left corner of the screen (hard coded numbers in chrome/browser/devtools/devtools_window.cc).

It looks like our window sizer logic (browser/ui/window_sizer/window_sizer.cc) is taking those numbers, but not taking into account the external display resolution.

@OP: This should be a workaround that doesn't involve restarting your OS:
- Use the Chrome profile switcher to use a fresh profile, e.g. Guest (https://support.google.com/chrome/answer/2364824)
- Move the newly opened Guest's Chrome window into the high resolution monitor's top left corner
- Open it's DevTools with F12

If that doesn't work, any saved window placement preferences will show up in your profile's "Preferences" file under a "browser" > "app_window_placement" > "DevToolsApp" entry.  The preferences file is located in "AppData\Local\Google\Chrome\User Data\".  Please let us know if the first workaround I suggested works or not first.

@WindowManager team, can someone confirm this, have you seen similar issues before?

Hi guys,
Solution 1, with guest profile does not work. Precisely it works but only with the Guest profile and if I switch back to my Default profile I do have the problem. It does not surprise me because it looks like browinsg as Guest profile creates a new json config with different values.

Manually editing the json config worked. I did have a Json with these values
DevToolsApp":{"always_on_top":false,"bottom":4801,"docked":false,"left":6261,"maximized":false,"right":12037,"top":2625,"work_area_bottom":1080,"work_area_left":1536,"work_area_right":3456,"work_area_top":0}

I replaced them by smaller values (e.g. 100) and my devtools are back.

Thank you

Glad you found a workaround.  Since this isn't really DevTools related, removing DevTools label.

Thank you for providing more feedback. Adding requester "hdodda@chromium.org" for another review and adding "Needs-Review" label for tracking.

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

As per comment #11 , @benoit.patra-- could you please confirm us whether we can close this issue.

Thanks!

The bug is still here. I would not close it.

comment #11 states a workaround can be found.

Thank you for providing more feedback. Adding requester "hdodda@chromium.org" for another review and adding "Needs-Review" label for tracking.

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

Issue has not been modified or commented on in the last 365 days, please re-open or file a new bug if this is still an issue.

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