It turns out that the README for the xeventbind PKGBUILD actually works
very well here. On another note, I've yet to figure out how exactly I
want to document PKGBUILDs.
This is an X-specific script that changes (mostly) everything that needs
to be changed on resolution change, with the exception of X cursor size.
Note that any programs already running are not affected. For this kind
of functionality, you probably want to use Wayland instead.