From bbfc0a63e1e682560864fa033b197ce65e65b839 Mon Sep 17 00:00:00 2001
From: Steven Peckins <sep16@psu.edu>
Date: Tue, 10 Apr 2012 18:49:03 -0400
Subject: [PATCH 1/2] Add Element.scrollIntoViewIfNecessary(); use in
 markNext/markPrevious

Element.scrollIntoViewIfNecessary() only scrolls the parent container if
the element is not already entirely within view.  This solves two
related issues for autocomplete dropdowns when there are scrollbars.
First, "changing direction" while scrolling through choices is no longer
a jarring user experience.  Second, when the autocomplete element is
within a containing element with its own scrollbars, scrollIntoView
would scroll the outer scroll bars, moving the LI.selected to the top
and obscuring the INPUT element.
---
 src/controls.js | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/controls.js b/src/controls.js
index cde682f..8484422 100644
--- a/src/controls.js
+++ b/src/controls.js
@@ -211,13 +211,13 @@ Autocompleter.Base = Class.create({
   markPrevious: function() {
     if(this.index > 0) this.index--;
       else this.index = this.entryCount-1;
-    this.getEntry(this.index).scrollIntoView(true);
+    this.getEntry(this.index).scrollIntoViewIfNecessary(true);
   },
 
   markNext: function() {
     if(this.index < this.entryCount-1) this.index++;
       else this.index = 0;
-    this.getEntry(this.index).scrollIntoView(false);
+    this.getEntry(this.index).scrollIntoViewIfNecessary(false);
   },
 
   getEntry: function(index) {
@@ -960,4 +960,16 @@ Form.Element.DelayedObserver = Class.create({
     this.timer = null;
     this.callback(this.element, $F(this.element));
   }
-});
\ No newline at end of file
+});
+
+Element.addMethods({
+  scrollIntoViewIfNecessary: function(element, showAtTop) {
+    element = $(element);
+    var parent = element.getOffsetParent(), y = element.offsetTop;
+    if (parent.scrollTop > element.offsetTop || parent.scrollTop < (element.offsetTop - parent.offsetHeight + element.offsetHeight)) {
+      parent.scrollTop = (showAtTop || typeof(showAtTop) == 'undefined')
+        ? element.offsetTop
+        : element.offsetTop - parent.offsetHeight + element.offsetHeight;
+    }
+  }
+});

From 83a996ef4c79c5b71778839305d067ed5f330852 Mon Sep 17 00:00:00 2001
From: Steven Peckins <sep16@psu.edu>
Date: Tue, 8 May 2012 16:08:57 -0400
Subject: [PATCH 2/2] Add 'return element' to scrollIntoViewIfNecessary

---
 src/controls.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/controls.js b/src/controls.js
index 8484422..553a3ad 100644
--- a/src/controls.js
+++ b/src/controls.js
@@ -971,5 +971,6 @@ Element.addMethods({
         ? element.offsetTop
         : element.offsetTop - parent.offsetHeight + element.offsetHeight;
     }
+	return element;
   }
 });