window--sanitize-window-sizes

window--sanitize-window-sizes is a compiled Lisp function in `window.el'.

(window--sanitize-window-sizes FRAME HORIZONTAL)

Assert that all windows on FRAME are large enough.
If necessary and possible, make sure that every window on frame
FRAME has its minimum height. Optional argument HORIZONTAL
non-nil means to make sure that every window on frame FRAME has
its minimum width. The minimum height/width of a window is the
respective value returned by `window-min-size' for that window.

Return t if all windows were resized appropriately. Return nil
if at least one window could not be resized as requested, which
may happen when the FRAME is not large enough to accommodate it.