1 files changed, 30 insertions, 8 deletions

diff --git a/firmware/scroll_engine.c b/firmware/scroll_engine.c
index 200695b5d6..9607c90448 100644
--- a/firmware/scroll_engine.c
+++ b/firmware/scroll_engine.c
@@ -84,6 +84,18 @@ void lcd_stop_scroll(void)
     lcd_scroll_info.lines = 0;
 }
 
+/* returns true if the 'line' in 'lines_vp' would scroll into 'othervp' */
+static bool line_overlaps_viewport(struct viewport *lines_vp, int line,
+                                   struct viewport *othervp)
+{
+    int y = (font_get(lines_vp->font)->height*line) + lines_vp->y;
+    if (y < othervp->y || y > othervp->y + othervp->height)
+        return false;
+    else if ((lines_vp->x + lines_vp->width < othervp->x) ||
+             (othervp->x + othervp->width < lines_vp->x))
+        return false;
+    return true;
+}
 /* Stop scrolling line y in the specified viewport, or all lines if y < 0 */
 void lcd_scroll_stop_line(struct viewport* current_vp, int y)
 {
@@ -91,8 +103,11 @@ void lcd_scroll_stop_line(struct viewport* current_vp, int y)
 
     while (i < lcd_scroll_info.lines)
     {
-        if ((lcd_scroll_info.scroll[i].vp == current_vp) && 
-            ((y < 0) || (lcd_scroll_info.scroll[i].y == y)))
+        if (((lcd_scroll_info.scroll[i].vp == current_vp) && 
+                ((y < 0) || (lcd_scroll_info.scroll[i].y == y))) ||
+            ((lcd_scroll_info.scroll[i].vp != current_vp) &&
+                line_overlaps_viewport(lcd_scroll_info.scroll[i].vp, 
+                                   lcd_scroll_info.scroll[i].y, current_vp)))
         {
             /* If i is not the last active line in the array, then move
                the last item to position i */
@@ -102,8 +117,10 @@ void lcd_scroll_stop_line(struct viewport* current_vp, int y)
             }
             lcd_scroll_info.lines--;
 
-            /* A line can only appear once, so we're done. */
-            return ;
+            /* A line can only appear once, so we're done, 
+             * unless we are clearing the whole viewport */
+            if (y >= 0)
+                return ;
         }
         else
         {
@@ -165,8 +182,11 @@ void lcd_remote_scroll_stop_line(struct viewport* current_vp, int y)
 
     while (i < lcd_remote_scroll_info.lines)
     {
-        if ((lcd_remote_scroll_info.scroll[i].vp == current_vp) && 
-            ((y < 0) || (lcd_remote_scroll_info.scroll[i].y == y)))
+        if (((lcd_remote_scroll_info.scroll[i].vp == current_vp) && 
+                ((y < 0) || (lcd_remote_scroll_info.scroll[i].y == y))) ||
+            (((lcd_remote_scroll_info.scroll[i].vp != current_vp) &&
+                line_overlaps_viewport(lcd_scroll_info.scroll[i].vp, 
+                                   lcd_scroll_info.scroll[i].y, current_vp))))
         {
             /* If i is not the last active line in the array, then move
                the last item to position i */
@@ -176,8 +196,10 @@ void lcd_remote_scroll_stop_line(struct viewport* current_vp, int y)
             }
             lcd_remote_scroll_info.lines--;
 
-            /* A line can only appear once, so we're done. */
-            return ;
+            /* A line can only appear once, so we're done, 
+             * unless we are clearing the whole viewport */
+            if (y >= 0)
+                return ;
         }
         else
         {