Make undo-tree not use a separate frame

since it works poorly, causing jumping back and forth

.emacs.d/init.el

@@ -451,6 +451,8 @@
 
 (use-package frames-only-mode :ensure
   :config
+  ; seems to need to be before mode init
+  (add-to-list 'frames-only-mode-use-window-functions 'undo-tree-visualize)
   (frames-only-mode t)
   (menu-bar-mode 0)
   (defun split-window-below-i3 ()