Nice of you to suggest Glib, which appears to be useful for many functions besides events.
My needs at present are really pedaestrian--just a couple of basic watchers--only complicated because the app I'm working on has terminal-based and Tk-GUI interfaces. I pretty much have to use Tk::event for the Tk and Tk/ReadLine side. I have similar watchers written using Event.pm for the text interface, because I don't want to force Tk on people who might be console users.
So it won't be both loops together. Just one of the other. It looks like AnyEvent will let me code identically to both Event and Tk::event backends, as well as to Glib or Wx if I decide I want to snazz up my GUI.