[Xmonad] darcs patch: first shot at a floating layer

[Donald Bruce Stewart]

droundy:
> Another couple of ideas for the float layer:
> 
> mod1-button2 should raise a window that's not at the top, but lower to the
> very bottom one that's already on top.  Otherwise it can be hard to find
> obscured windows.  But once this behavior is configurable, of course, this
> change will be less critical.
> 
> When dragging a window, I'd rather it was displayed is it'll be when I
> release it.  Currently the window is raised to the top while being dragged,
> but then released at the current stacking level, with the result that you
> can easily "lose" the window you're dragging, if you drop it under a larger
> window.  This change wouldn't prevent that loss, but would make it obvious,
> since the window would be hidden when you drag it under the larger one.
> Another solution would be to always raise windows when moving them.

Yes, that's better behaviour.