'Changed

1 files changed, 20 insertions, 10 deletions

diff --git a/ui/jquery.ui.core.js b/ui/jquery.ui.core.js
index 934210348..2f238a01c 100644
--- a/ui/jquery.ui.core.js
+++ b/ui/jquery.ui.core.js
@@ -149,17 +149,27 @@ $.fn.extend({
 		if (zIndex !== undefined) {
 			return this.css('zIndex', zIndex);
 		}
-
-		var elem = this[0];
-		while (elem && elem.style) {
-			// IE returns 0 when zIndex is not specified
-			// other browsers return an empty string
-			// we ignore the case of nested elements with an explicit value of 0
-			// <div style="z-index: -10;"><div style="z-index: 0;"></div></div>
-			if (elem.style.zIndex !== '' && elem.style.zIndex !== 0) {
-				return +elem.style.zIndex;
+		
+		if (this.length) {
+			var elem = $(this[0]), position, value;
+			while (elem.length && elem[0] !== document) {
+				// Ignore z-index if position is set to a value where z-index is ignored by the browser
+				// This makes behavior of this function consistent across browsers
+				// WebKit always returns auto if the element is positioned
+				position = elem.css('position');
+				if (position == 'absolute' || position == 'relative' || position == 'fixed')
+				{
+					// IE returns 0 when zIndex is not specified
+					// other browsers return a string
+					// we ignore the case of nested elements with an explicit value of 0
+					// <div style="z-index: -10;"><div style="z-index: 0;"></div></div>
+					value = parseInt(elem.css('zIndex'));
+					if (!isNaN(value) && value != 0) {
+						return value;
+					}
+				}
+				elem = elem.parent();
 			}
-			elem = elem.parentNode;
 		}
 
 		return 0;