From 6135cc5c028fd3b81e26f63dd3208fd31a5ce213 Mon Sep 17 00:00:00 2001
From: cage <cage-invalid@invalid>
Date: Sun, 6 Sep 2020 11:18:49 +0200
Subject: [PATCH] - fixed  'line-oriented-window:row-move' must  return always 
 a number   (0), not nil, when no movement occurs;

- fixed vertical scrolling boundaries of messages window.
---
 src/line-oriented-window.lisp | 25 +++++++++++++------------
 src/message-window.lisp       | 28 +++++++++++++++++++++++-----
 2 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/src/line-oriented-window.lisp b/src/line-oriented-window.lisp
index cf09e7e..9ca3ee2 100644
--- a/src/line-oriented-window.lisp
+++ b/src/line-oriented-window.lisp
@@ -221,18 +221,19 @@ actual of  rows moved. This can  be different from `amount'  if moving
 this exact quantity wold go beyond the length or fows or zero."
   (with-accessors ((rows               rows)
                    (row-selected-index row-selected-index)) object
-    (when (/= 0 amount)
-      (let* ((desired-amount (+ amount row-selected-index))
-             (actual-amount  (if (< amount 0)
-                                 (max (- desired-amount
-                                         row-selected-index)
-                                      (- row-selected-index))
-                                 (- (min desired-amount
-                                         (1- (length rows)))
-                                    row-selected-index))))
-        (select-row object (+ row-selected-index
-                              actual-amount))
-        actual-amount))))
+    (if (/= 0 amount)
+        (let* ((desired-amount (+ amount row-selected-index))
+               (actual-amount  (if (< amount 0)
+                                   (max (- desired-amount
+                                           row-selected-index)
+                                        (- row-selected-index))
+                                   (- (min desired-amount
+                                           (1- (length rows)))
+                                      row-selected-index))))
+          (select-row object (+ row-selected-index
+                                actual-amount))
+          actual-amount)
+        0)))
 
 (defclass simple-line-navigation-window (wrapper-window row-oriented-widget border-window)
   ((selected-line-bg
diff --git a/src/message-window.lisp b/src/message-window.lisp
index ed6b646..0a55800 100644
--- a/src/message-window.lisp
+++ b/src/message-window.lisp
@@ -166,9 +166,26 @@
     (when prepare-for-rendering
       (prepare-for-rendering object :jump-to-first-row jump-to-first-row))))
 
+(defun offset-to-move-end (win)
+  (with-accessors ((rows                 rows)
+                   (row-selected-index   row-selected-index)) win
+    (let ((win-height (win-height-no-border win)))
+      (- (- (length rows)
+            (- win-height 1))
+         row-selected-index))))
+
+(defun scroll-end-reached-p (win)
+  (with-accessors ((rows                 rows)
+                   (row-selected-index   row-selected-index)) win
+    (let* ((win-height (win-height-no-border win))
+           (rows-left  (- (length rows) row-selected-index)))
+      (< rows-left
+         win-height))))
+
 (defmethod scroll-down ((object message-window) &optional (amount 1))
-  (when (/= (row-move object amount)
-            0)
+    (when (not (or (scroll-end-reached-p object)
+                   (= (row-move object amount)
+                      0)))
     (draw object)))
 
 (defmethod scroll-up   ((object message-window) &optional (amount 1))
@@ -179,9 +196,10 @@
 (defmethod scroll-end ((object message-window))
   (with-accessors ((rows                 rows)
                    (row-selected-index   row-selected-index)) object
-    (when (/= (row-move object (- (length rows) row-selected-index))
-              0)
-      (draw object))))
+    (let ((offset (offset-to-move-end object)))
+      (when (/= (row-move object offset)
+                0)
+        (draw object)))))
 
 (defmethod scroll-begin  ((object message-window))
   (with-accessors ((rows                 rows)