Re: Suggesting `frame-split-biggest-window' Re: customize location and shape of a new window in a frame

[martin rudalics]

> If there was a function (frame-split-biggest-window FRAME SIZE SIDE
> PIXELWISE) to split the "biggest" [*] window in the frame, then
> neither BBDB nor any other Elisp code would need to keep reinventing
> this wheel.
>
> (The other two functions, more for interactive use, would be
> `frame-split-biggest-window-below' and
> `frame-split-biggest-window-right'.)
>
> [*] To find the "biggest" window when splitting below, find the
> tallest window or windows and split the widest of them; when
> splitting right, find the widest window or windows and split the
> tallest of them.

We have a number of options for that.  One of them is the option
'split-window-preferred-function' (a misnomer) which is by default set
to 'split-window-sensibly'.  Consult their definitions first.  The
latter's behavior is guided by the options 'split-height-threshold'
and 'split-width-threshold' (two more misnomers) .  Together, these
should provide a boilerplate for writing your own function which you
can then put into 'display-buffer-alist'.

One functionality Emacs is sadly lacking is that of orderly setting up
and saving compositions of windows in form of a rectangle.  Eclipse
calls these "perspectives", in Emacs the concept of "window state"
comes most closely.  Currently, you have to set up such a state by
using a sequence of 'split-window' calls which requires to know the
intrinsics of window splitting, the relationship of parent and child
windows, window combinations and the like.  Using 'display-buffer' for
setting up states will hardly produce good results.

It would be nice to have some sort of basic, prefabricated layouts
like the ones you sketched and choose from them (though a four window
layout with a different window in each corner of them frame would
still require to know whether the root window is a vertical or
horizontal combination).  But I have no good idea yet which layout
types are really needed and how to provide a suitable interface for
accessing them.  IIRC the "Emacs IDE" had provisions for them but I
have not heard from its developers for years.

martin