From e9024292cdfce5906f37f6da71a7521d6ac86c60 Mon Sep 17 00:00:00 2001
From: DanielApt <daniel@knowsis.com>
Date: Sun, 8 Nov 2015 22:03:35 +0000
Subject: [PATCH] Fix broken drag scrolling when top is out of viewport

Addresses issue no. 390 #390
---
 src/js/plugin/handler/drag-scrollbar.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/js/plugin/handler/drag-scrollbar.js b/src/js/plugin/handler/drag-scrollbar.js
index 060b30a..8fcbe79 100644
--- a/src/js/plugin/handler/drag-scrollbar.js
+++ b/src/js/plugin/handler/drag-scrollbar.js
@@ -60,7 +60,12 @@ function bindMouseScrollYHandler(element, i) {
 
   function updateScrollTop(deltaY) {
     var newTop = currentTop + (deltaY * i.railYRatio);
-    var maxTop = i.scrollbarYRail.getBoundingClientRect().top + (i.railYRatio * (i.railYHeight - i.scrollbarYHeight));
+    var scrollbarYTop = i.scrollbarYRail.getBoundingClientRect().top;
+
+    if(scrollbarYTop < 0) {
+      scrollbarYTop = 0;
+    }
+    var maxTop = scrollbarYTop + (i.railYRatio * (i.railYHeight - i.scrollbarYHeight));
 
     if (newTop < 0) {
       i.scrollbarYTop = 0;