#Firefox hack: in about:config, set full-screen-api.ignore-widgets to True. From now on, hitting F11 will go "fullscreen" within the current Firefox window boundary (rather than covering the entire screen). Very handy if you need to have a smaller window hanging somewhere in the corner, with some watchdog-like data or weather or whatnot.
@linmob, with pmOS patch applied, this is actually the behavior after F11 twice. Never dig into it to find out why though.
@xpil I discovered a problem using this function with the Picture-in-Picture-mode.
It starts in this fullscreen-mode, too, but the borders are gone and applying settings from the window-manager is now impossible, since the last pixel, that you could right-click, without knowing shortcuts is gone.
@xpil, you might be interested in an add-on I published a while ago: https://addons.mozilla.org/en-US/firefox/addon/alful
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