A numeric argument, n , moves several steps in the cyclic order of windows. A negative numeric argument moves around the cycle in the opposite order. See section Editing in the Minibuffer . However, unlike other-window , this command selects a window on the next or previous frame instead of wrapping around to the top or bottom of the current frame, when there are no more windows. Like C-v , it takes positive and negative arguments.
Comparison starts at point in each window.
Point moves forward in each window, a character at a time, until the next set of characters in the two windows are different. Then the command is finished. A prefix argument ignore-whitespace means ignore changes in whitespace. Different C-x 4 commands have different ways of finding the buffer to select. C-x 4 b bufname RET Select buffer bufname in another window.