`auto-side-windows-mode' sends a buffer to the left, the right, the top
or the bottom side window of the frame, by the name of the buffer, its
major mode, or any condition `buffer-match-p' takes.

Commands toggle a buffer out of its side window and back, send one to a
side the rules do not name, and move a buffer from slot to slot along
its side, by key or by a drag of the header line.

The size of a side and the size of each of its slots can be
remembered per tab, so a layout you resize comes back as you left it.