Datepicker: Don't use .zIndex(); implement the logic locally.

Author: scottgonzalez

ui/jquery.ui.datepicker.js

@@ -19,6 +19,28 @@ var PROP_NAME = "datepicker",
 	dpuuid = new Date().getTime(),
 	instActive;
 
+function getZindex( elem ) {
+	var 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" ), 10 );
+			if ( !isNaN( value ) && value !== 0 ) {
+				return value;
+			}
+		}
+		elem = elem.parent();
+	}
+
+	return 0;
+}
 /* Date picker manager.
    Use the singleton instance of this class, $.datepicker, to interact with the date picker.
    Settings for (groups of) date pickers are maintained in an instance object,
@@ -744,7 +766,7 @@ $.extend(Datepicker.prototype, {
 		if (!inst.inline) {
 			showAnim = $.datepicker._get(inst, "showAnim");
 			duration = $.datepicker._get(inst, "duration");
-			inst.dpDiv.zIndex($(input).zIndex()+1);
+			inst.dpDiv.css( "z-index", getZindex( $( input ) ) + 1 );
 			$.datepicker._datepickerShowing = true;
 
 			if ( $.effects && $.effects.effect[ showAnim ] ) {