window--atom-check

window--atom-check is a compiled Lisp function in `window.el'.

(window--atom-check &optional FRAME)

Check atomicity of all windows on FRAME.
FRAME defaults to the selected frame. If an atomic window is
wrongly configured, reset the atomicity of all its windows on
FRAME to nil. An atomic window is wrongly configured if it has
no child windows or one of its child windows is not atomic.