window--resize-siblings

window--resize-siblings is a compiled Lisp function in `window.el'.

(window--resize-siblings WINDOW DELTA &optional HORIZONTAL IGNORE TRAIL EDGE CHAR-SIZE)

Resize other windows when WINDOW is resized vertically by DELTA pixels.
Optional argument HORIZONTAL non-nil means resize other windows
when WINDOW is resized horizontally by DELTA pixels. WINDOW
itself is not resized by this function.

The optional argument IGNORE has the same meaning as for
`window-resizable'.

Optional arguments TRAIL and EDGE, when non-nil, refine the set
of windows that shall be resized. If TRAIL equals `before',
resize only windows on the left or above EDGE. If TRAIL equals
`after', resize only windows on the right or below EDGE. Also,
preferably only resize windows adjacent to EDGE.