The playback problems with the JS decoder are due to bugs in some versions of Firefox for Linux. Those have been recently fixed (as of 19.02a as far as I can tell). See: https://github.com/ofmlabs/aurora.js/issues/13
Is there a good reason why the lyrics text is not right-aligned? I understand symmetry looks better in such a design, but it's much easier to follow along with a song when you don't have to consciously look for the beginning of the next line.
A sensible tiling window manager doesn't tile popup windows (and I believe xmonad is sensible). If it doesn't float popups, then you just haven't configured it to do so. Can't blame you, though. Writing Haskell to configure a window manager isn't exactly a one-step process. I think parts of the following resource will prove useful if you ever decide to give xmonad another try: http://www.haskell.org/haskellwiki/Xmonad/General_xmonad.hs_...
I think more people should write similar extensions or even new
window managers. In my opinion, “traditional” window management is
quirky, even if we've all grown used to it. Resizing and moving
windows, for example, are painful given how you need to click on
small specific areas to carry them out. Most window managers on
Linux have overcome with a combination of a key press and mouse
click allowing you to move/resize by clicking anywhere in the
window. With a tiling window manager you usually have some
keyboard shortcut to do it.
Still, none of those approaches solve the problem in all
situations. Managing windows can be “uncomfortable”. Sure you can
make use of workspaces, or tags (à la dwm, I think the tag
paradigm is beautiful) or whatnot, but you don't want to think
about the act of switching windows. Have you ever found yourself
alt-tabbing through a pile of windows and be annoyed by not
getting to the right window easily enough (“Oh, drat, I pressed
Tab one too many times”). Whenever I have to use OS X, I press the
Exposé shortcut for almost every context switch.
So yeah, this is kind of extension is more than welcome and others should continue to innovate. If nothing else good comes out of Gnome 3, at least it would have pushed people to think about their interaction with the interface.