1) I like titlebars but find that the decorators (e.g. noFrillsDeco) do
not apply to floating windows. Is there a way to decorate the floats too?
I don't think so.
Even better: is there a way to apply decorations only to certain windows
(i.e. in the manageHook)?
Only if you can do it by sending a message to the layout modifier or by storing information in ExtensibleState. (That is, you'll have to write your own layout modifier based on Decoration.)
Note also that, as currently written, Decoration is quadratic in both the number of managed windows *and* in the number of decorations applied to a window; this means things get rather slow if you have a lot of windows or a lot of decorations (not to say both!).
2) The floating windows are always in front of tiled windows. This is
annoying: i would like to be able to script something so that the floating
layer is hidden if a tiled window is focused. Is there some command along
the lines of "hide all floats"?