I am running macOS High Sierra (10.13.6) and using Chrome (71.0.3578.98). I am a web developer and want to quickly activate the "Device Toolbar" via a keyboard shortcut so I can toggle between views for desktop and mobile.

When I have the DevTools window open on a site and hover over the icon that allows me to do this via mouse click it says there's a shortcut of Command+Shift+M.

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However, whenever I press this key combination nothing happens. There is a similar key combination shortcut of Command+Shift+C that allows me to "Select an element in the page to inspect it" which works without issue.

I have removed and deselected any system-wide macOS shortcuts that would use this key combination. Similarly, I don't have any app-specific shortcuts configured in the system settings for Chrome that use this key combination. Finally, I have no other third-party app running which overrides or blocks this key combination.

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Why isn't this working as expected?

  • Very odd. FWIW, I just tried this on my MacBook Air (2018) running macOS Mojave (10.14.2) and it works as expected. Not great comfort to you I know, but still it works on my setup. FWIW, I just have Chrome installed but I never really use it much at all past web-page testing. Dec 28, 2018 at 18:41
  • Thanks @JakeGould yeah it's so weird. I have never had it work. I have a pretty basic install of software on my system with nothing crazy. It has bugged me for quite a while and today was the last straw. Hoping someone can chime in with help.
    – Art Geigel
    Dec 28, 2018 at 19:56
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    Just for fun I decided to review my Chrome Extensions to see if there was anything that might be impacting it and to my surprise there was. I installed a "Mute Tab" extension a long time ago that I have since forgot about entirely. Within it's keyboard shortcuts section I had that key combination used to mute a tab. So annoyed and angry at myself! Posting my answer in case it helps someone else.
    – Art Geigel
    Dec 28, 2018 at 20:07
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    Lol! Definitely post that as an answer. And for whatever it’s worth the lesson is basically: Review system settings and always double-check installed plugins. Dec 28, 2018 at 20:10

1 Answer 1


This all boils down to a problem I created myself. I had installed an extension long ago that I had forgotten about—called "Mute Tab Shortcuts"—and the keyboard shortcut was set to Command+Shift+M. I reset it to something else and now the Chrome combination to activate "Device Toolbar" is working as intended.

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If you're running into similar problems I'd suggest reviewing your Keyboard shortcuts within Chrome first at chrome://extensions/shortcuts

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  • Great answer to a common—but often forgotten—issue. Dec 28, 2018 at 20:23

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