User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36 Steps to reproduce: 1. Browse the link "https://mozilla.github.io/webrtc-landing/" from Firefox browser 2. Click "Try Demo" on getUserMedia example tab. 3. Open a few application windows like Excel, PPT, MS Word Docs..etc 4. Select "Window" tab on Firefox WebRTC sample page to share available windows. 5. Try to check the newly opened windows in step #3 are available in the list of windows that Firefox browser is showing. Actual results: List of windows available are displaying only the windows opened before launching the Firefox browser. The app windows opened after the Firefox browser launch are missing in the list. Expected results: List should be updated dynamically to show all windows available on the machine.

Please try in latest Nightly and re-file with platform and firefox version if not fixed.