User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0 Build ID: 20170312084740 Steps to reproduce: - Open developer tools and click on 'Show in separate window' button. - Click on Responsive Design Mode button or use 'Ctrl-Shift-m' shortcut. Running on Mint 18.1. Actual results: Nothing - unable to enter or exit RDM from the Developer Tools window. Expected results: Should have entered/exited RDM.

Old bug, so probably already filed. You have to focus on the tab before entering RDM with dev tools undocked.

Tab is focused. I can enter/exit RDM from the tab itself using the keyboard shortcut, but nothing works in the Dev Tools window.

You're right, it's a recent regression. :) Reg range: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=83e1a88a9833a498a0e841e37a822de99b0ed0c6&tochange=f6895ed1367c698cd60af71084f68950cdb2e630 Alexandre Poirot — Bug 1320149 - Prevent loading gcli when opening a toolbox. r=jwalker,miker

The browser console shows: "browserWindow.gBrowser" pointing to: https://dxr.mozilla.org/mozilla-central/source/devtools/client/definitions.js#516

(In reply to Tim Nguyen :ntim from comment #4) > The browser console shows: > > "browserWindow.gBrowser" meant "browserWindow.gBrowser is undefined"

Tracking 54/55+ for this recent regression in Dev Tools.

Probably worth a test so we avoid regressing this.

Comment on attachment 8847683 [details] Bug 1346647 - Fix RDM button for undocked toolbox. https://reviewboard.mozilla.org/r/120598/#review123382 Nice catch. I'm wondering other usage of this "toolbox.win.top" are also wrong? Looks like this one could be as wrong: http://searchfox.org/mozilla-central/source/devtools/client/framework/devtools-browser.js#754

(In reply to Tim Nguyen :ntim from comment #9) > Probably worth a test so we avoid regressing this. Perhaps so! I don't think I have time to write it right now, but I agree it would be good to have...

Comment on attachment 8847683 [details] Bug 1346647 - Fix RDM button for undocked toolbox. https://reviewboard.mozilla.org/r/120598/#review123382 Looks like that's the only other usage of `toolbox.win.top`. Since it landed at a different time and may or may not need uplifting, I filed bug 1348318 about this other usage.

Pushed by jryans@gmail.com: https://hg.mozilla.org/integration/autoland/rev/576abf29e19c Fix RDM button for undocked toolbox. r=ochameau

Comment on attachment 8847683 [details] Bug 1346647 - Fix RDM button for undocked toolbox. Approval Request Comment [Feature/Bug causing the regression]: Bug 1320149 caused this when refactoring the DevTools toolbox buttons [User impact if declined]: If declined, the button to toggle Responsive Design Mode won't work when the toolbox is undocked [Is this code covered by automated tests?]: No [Has the fix been verified in Nightly?]: Yes [Needs manual test from QE? If yes, steps to reproduce]: No [List of other uplifts needed for the feature/fix]: None [Is the change risky?]: No [Why is the change risky/not risky?]: DevTools only, only affects a single button [String changes made/needed]: None

Comment on attachment 8847683 [details] Bug 1346647 - Fix RDM button for undocked toolbox. Fix an RDM icon regression issue. Aurora54+.

I have reproduced this bug with Firefox nightly 55.0a1 (2017-03-12) on Windows 10, 64 Bit. The Bug's fix is now verified on latest nightly 55.0a1 (2017-03-22) and latest developer edition 54.0a2 (2017-03-22) . developer edition 54.0a2 : Build ID 20170322004022 User Agent Mozilla/5.0 (Windows NT 10.0; WOW64; rv:54.0) Gecko/20100101 Firefox/54.0 nightly 55.0a1: Build ID 20170322030208 User Agent Mozilla/5.0 (Windows NT 10.0; WOW64; rv:55.0) Gecko/20100101 Firefox/55.0 [bugday-20170322]