add iscroll and change vertical scroll bar configuration

settings/gui-settings.el

@@ -46,49 +46,26 @@
   ;; `scroll-bar-mode' sets for all frames and all windows
   ;; use `set-window-scroll-bars' for windows only
   (scroll-bar-mode 0)  ;; 1st deactivate scrolling
-  (add-hook 'visual-line-mode-hook 'my-visual-line-mode-hook)
-  (defun my-visual-line-mode-hook ()
-    "no `horizontal-scroll-bar' if `visual-line-mode'"
-    (if visual-line-mode
-        (set-window-scroll-bars (frame-selected-window) nil t nil nil)
-      (set-window-scroll-bars (frame-selected-window) nil t nil 'bottom)
-      ))
-  (add-hook 'window-state-change-hook
-            (lambda () (my-window-state-change (window-buffer))))
-  (defun my-window-state-change (frame-or-window)
-    (let (window
-          (vertical-type nil)
-          (horizontal-type nil)
-          buffer
-          buffer-name)
-      (when (framep frame-or-window)
-        (setq window (frame-selected-window frame-or-window)))
-      (setq buffer (window-buffer window))
-      (setq buffer-name (buffer-name buffer))
-      ;; turn scrolling on
-      (when visual-line-mode
-        (setq vertical-type 'right)
-        (setq horizontal-type nil))
-      (when truncate-lines
-        (setq vertical-type 'right)
-        (setq horizontal-type 'bottom))
-      ;; turn off
-      (cond
-       ((or (minibufferp buffer)
-            (string-equal major-mode "doc-view-mode")
-            (string-equal buffer-name " *Org tags*"))
-        (setq vertical-type nil)
-        (setq horizontal-type nil))
-       ((string-prefix-p "*mu4e" buffer-name)
-        (setq vertical-type 'right)))
-      ;; (message "%s %s %s %s %s"
-      ;;          buffer-name
-      ;;          visual-line-mode
-      ;;          truncate-lines
-      ;;          vertical-type
-      ;;          horizontal-type)
-      (set-window-scroll-bars window nil vertical-type nil horizontal-type)))
-  )
+  (defun my-window-scroll-function (window display-start)
+    "This function
+- is listed in `window-scroll-functions' which is called by
+  `set-window-buffer' before running `window-configuration-change-hook'
+  and therefore will be run on every vertical scroll event
+- will activate vertical scoll bar if not whole buffer height is
+  visible
+
+WINDOW: `window' object, its string will look like #<window 3 on gui-settings.el> and
+DISPLAY-START: `integer', e.g. 3820"
+    ;; (message "%s" window)
+    (let ((vertical-type nil)
+          (horizontal-type nil))
+      (unless (string-equal (format-mode-line "%p") "All")
+        (setq vertical-type 'right))
+      ;; `scroll-bar-mode' not used bc/ it's global, therefore:
+      (set-window-scroll-bars
+       window nil vertical-type nil horizontal-type nil)))
+  (add-to-list 'window-scroll-functions #'my-window-scroll-function)
+  )  ;; end of use-package emacs
 
 (use-package tab-bar
   :defer 0.5
@@ -471,6 +448,9 @@ See also `dashboard-insert-section'."
   :commands focus-mode
   :custom-face (focus-unfocused ((t :inherit shadow))))
 
+(use-package iscroll
+  :hook ((special-mode text-mode) . iscroll-mode))
+
 (use-package virtual-auto-fill
   :delight (virtual-auto-fill-mode "Ⓥｆ")
   :commands virtual-auto-fill-mode