[Affected versions]: - Firefox 52 beta 1 build 2 - latest Developer Edition 53.0a2 - latest Nightly 54.0a1 [Affected platforms]: - Windows 7 64-bit - macOS 10.12.2 - Ubuntu 16.04 64-bit [Steps to reproduce]: 1. Start Firefox. 2. Visit in a new tab the attached iframe. 3. Open inspector and activate grid tool. 4. Scroll inside the iframe. 5. Detach dev tools (show in separate window). Additional steps: 1. Start Firefox. 2. Visit in a new tab the attached iframe. 3. Open inspector and activate grid tool. 4. Resize Firefox and keep it that way. 5. Scroll inside the iframe. 6. Resize Firefox to its initial state. [Expected result]: - The grid is displayed without graphical issues. [Actual result]: - The grid is cut from where the dev tools was attached. This is also reproducible without the dev tools and by resizing Fx. If one scrolls inside the iframe after step 5, the grid will show normally again. [Regression range]: - I don't know if this is a recent regression, will investigate further ASAP.

[Additional Information]: - Also here is a screencast showing the issue in question: https://dl.dropboxusercontent.com/u/109148197/CSS%20Grid%20Inspector/iframe%20grid.mov (the files was 25MB so I could not upload it directly in Bugzilla)

I also reproduced this on old Nightly from 2016-11-17 where the toggle grid layout highlighter was first introduced so this is not a regression.

The patch in bug 1312103 should also fix this.

zer0, can you comment if bug 1312103 did fix this issue?

As mentioned in comment 3, I can't reproduce it anymore now that bug 1312103 has landed. Bogdan, I think you also confirm that in your report, so I'm going to close this bug as DUPLICATE; if I'm wrong feel free to reopen it!

(In reply to Matteo Ferretti [:zer0] [:matteo] from comment #5) > As mentioned in comment 3, I can't reproduce it anymore now that bug 1312103 > has landed. > Bogdan, I think you also confirm that in your report, so I'm going to close > this bug as DUPLICATE; if I'm wrong feel free to reopen it! Yes you are right. I also can't reproduce it anymore after bug 1312103 landed.