It is used by [browsertime](https://github.com/mozilla/browsertime/) when measuring "visual metrics" for pageload performance. But the simplest way to play with it is from the browser console. First, create a string pref with the name `layers.windowrecording.path` and set it to an absolute path to some directory. Then, restart Firefox, open the Browser Console (with devtools.chrome.enabled = true), and execute the following: ```js windowUtils.startFrameRecording() // now briefly interact with a web site in the browser, and then run: windowUtils.stopCompositionRecording(true) ``` A new folder in the chosen directory should appear and be populated with PNG files which contain screenshots from the Firefox window.
Bug 1592031 Comment 3 Edit History
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It is used by [browsertime](https://github.com/mozilla/browsertime/) when measuring "visual metrics" for pageload performance. But the simplest way to play with it is from the browser console. First, create a string pref with the name `layers.windowrecording.path` and set it to an absolute path to some directory. Then, restart Firefox, open the Browser Console (with devtools.chrome.enabled = true), and execute the following: ```js windowUtils.startCompositionRecording() // now briefly interact with a web site in the browser, and then run: windowUtils.stopCompositionRecording(true) ``` A new folder in the chosen directory should appear and be populated with PNG files which contain screenshots from the Firefox window.