[oS-EN] Screensaver problem

Hi, I have been observing for weeks that the screensaver + sleep display feature in XFCE was not triggering. And I just noticed that after I closed all firefox windows, it triggers again. My hypothesis is that firefox, which has several opened tabs with youtube windows, is blocking the screensaver. Notice that they are videos not running currently: they are all finished or paused in mid play for continuing at another time. Yet they seem to inhibit the screensaver. (system is as per signature) -- Cheers / Saludos, Carlos E. R. (from Telcontar, using openSUSE Leap 15.5)