diff -Naur grub-new5/grub-core/gfxmenu/gui_list.c grub-new6/grub-core/gfxmenu/gui_list.c
--- grub-new5/grub-core/gfxmenu/gui_list.c	2013-07-17 18:57:56.597740755 +0400
+++ grub-new6/grub-core/gfxmenu/gui_list.c	2013-07-17 20:07:37.664064169 +0400
@@ -148,6 +148,33 @@
                              self->theme_dir);
 
       self->need_to_recreate_scrollbar = 0;
+
+      /* Sanity checks. */
+      if (self->scrollbar_frame != 0 && self->scrollbar_thumb != 0)
+        {
+          grub_gfxmenu_box_t box = self->menu_box;
+          grub_gfxmenu_box_t frame = self->scrollbar_frame;
+          grub_gfxmenu_box_t thumb = self->scrollbar_thumb;
+          int box_vertical_pad = (box->get_top_pad (box)
+                                  + box->get_bottom_pad (box));
+          int frame_horizontal_pad = (frame->get_left_pad (frame)
+                                      + frame->get_right_pad (frame));
+          int frame_vertical_pad = (frame->get_top_pad (frame)
+                                    + frame->get_bottom_pad (frame));
+          int thumb_horizontal_pad = (thumb->get_left_pad (thumb)
+                                      + thumb->get_right_pad (thumb));
+          int thumb_vertical_pad = (thumb->get_top_pad (thumb)
+                                    + thumb->get_bottom_pad (thumb));
+          int scrollbar_height = self->bounds.height - box_vertical_pad;
+
+          if (self->scrollbar_width < frame_horizontal_pad
+                                      + thumb_horizontal_pad
+              || scrollbar_height < frame_vertical_pad + thumb_vertical_pad)
+            {
+              self->draw_scrollbar = 0;
+              return 0;
+            }
+        }
     }
 
   return (self->scrollbar_frame != 0 && self->scrollbar_thumb != 0);
@@ -228,8 +255,18 @@
   frame->set_content_size (frame,
                            scrollbar_width - frame_horizontal_pad,
                            tracklen);
-  int thumby = tracktop + tracklen * (value - min) / (max - min);
+  int thumby;
   int thumbheight = tracklen * extent / (max - min) + 1;
+  if (thumbheight >= thumb_vertical_pad)
+    {
+      thumby = tracktop + tracklen * (value - min) / (max - min);
+    }
+  else /* Rare occasion. Thumb height is too low.  */
+    {
+      thumbheight = thumb_vertical_pad;
+      thumby = tracktop + ((tracklen - thumb_vertical_pad) * (value - min)
+                           / (max - extent));
+    }
   thumb->set_content_size (thumb,
                            scrollbar_width - frame_horizontal_pad
                            - thumb_horizontal_pad,
@@ -584,7 +621,7 @@
     }
   else if (grub_strcmp (name, "scrollbar_width") == 0)
     {
-      self->scrollbar_width = grub_strtol (value, 0, 10);
+      self->scrollbar_width = grub_strtoul (value, 0, 10);
     }
   else if (grub_strcmp (name, "scrollbar") == 0)
     {