I would like agenda follow mode to not use a different frame, but the same frame where the agenda is showing. My agenda buffer is always showing in a frame divided vertically (into two windows, left and right), so the agenda buffer takes half of the frame (left window) and a random buffer is on the other half of it (right window). How to force the follow mode to use this buffer in the same frame? Thanks!
frame
in Emacs is what is called awindow
by Gnome or KDE or Xfce or any such desktop environment and that causes confusion, so you have to be precise. IIUC and using the Emacs terminology, you have a frame that's divided into two windows, with one window showing the agenda and the other showing some other buffer and you want that second window to be taken over by the agenda's follow mode files, instead of creating a new frame for that. Is that correct?