People using tiling window managers like i3 or sway should get friendly with this feature. It allows me to "full window" (note: not screen) netflix/amazon/YouTube videos in a tile which was impossible to do without PIP.
Either awesome or i3 used to allow me to fullscreen a video, then pop that fullscreen video out into it's own floating window, that I could then stick on top of all other windows, and make it stay on every workspace. Really cool way to get a hacky picture in picture mode way before firefox did this.
VLC has a feature called "float on top". Together with resizing, it allows basically something akin to picture in picture mode. You can use VLC to play YouTube videos by downloading them with youtube-dl. That is what I used before Firefox PiP mode was available in stable.
> [...] However, one may simply wish to consume the fullscreen UI, not actually fullscreen the application [...]
> This PR implements a fullscreen inhibition feature in sway. When inhibited, sway will answer fullscreen requests correctly, but will not fullscreen the container.
Hmm, that worked for me in i3 before but not in bspwm.
I tried FF PiP recently, but I have "bspwm config honor_size_hints true" and that makes the window resize itself until it's the size of a postage stamp.
I3 can already do floating sticky windows which is essentially the same thing. It used to be possible to pop Chrome into a floating window from full screen but now both browsers fall out of full screen when floating - maybe this will bring it back - or is that what you meant?
I was very pleasantly surprised to see how well this worked with i3, even if it was technically possible to get something equivalent with a lot of button presses, Firefox PIP is a lot easier.
For Chrome users, I was using the "Windowed - floating Youtube/every website" plugin to achieve the same effect. It also gives you the control UI, which PiP doesn't have yet.
This is not my experience. I see no added value in this PIP.
I use XMonad, which is a tiling window manager. I've always been able to put a video into applicative full screen, then switch the layout to whatever I want. E.g. 2 browsers windows each playing a borderless video.
Before XMonad, I remember that when I switched to another workspace/window and back, my browser window would have stopped being fullscreen.
I'd rather have Firefox not adding hacks to work around the flaws of mainstream window managers.
There's a reason I mentioned only i3 and sway, they stick to managing _windows_ and thus only inform the application of their window size. Screen size is unabated by them, thus when applications that have a full screen mode size-up they get the real screen size. I3 author(s) specify purity as their reasoning for this and I actually agree with them. There are some other nuances with full screen that tie into this, too, such as signalling to the app to enter full screen instead of simply resizing the applications window means in most cases the user gets a more intuitive result.
XMonad's[0] default behaviour of being able to separately tell a program to go "fullscreen" (i.e. hide most UI) and control what portion of the screen its window takes up is extremely valuable, since many programs don't give you the option of separately hiding their UI, and it's only possible by making them go fullscreen. However, being able to hide the UI is actually most valuable when there is more than one window on the screen... This is especially important when you have a small (or average-sized) screen, but it's also useful on larger ones to avoid distractions.
Getting the "normal" fullscreen is just two keyboard shortcuts away ("fullscreen" the program and assign its window the entire screen), rather than one. From an intuitiveness point of view, being able to hide a program's UI and change its window size separately is arguably more intuitive — according to the separation of concerns, the former is managed by the program itself and the latter by the WM.
PiP is really nice, but videos aren't the content for which getting a distraction-free experience is most important...
[0] I'm sure that it's also possible with other tiling WMs such as ratpoison, stumpwm, awesome etc.
