Re: window groups

[martin rudalics]

> By "splitting at the top of the window tree":   As far as I know,
> right now the only way to create a new window (in an existing
> frame) is to split an existing window horizontally or vertically.
> New windows are always created by dividing a leaf node of the
> window tree.    The new functionality would be to support
> splitting the root window of a frame.

Here

(split-window nil nil nil nil t 'root)

gets me a new window above all others regardless how complex my
window-layout is.

>> Returning "precisely" to former sizes is non-trivial.
>
> How so?

Because your context might have changed in between.  For example, when
leaving a `save-window-excursion' you don't want your frame get resized.