fix for #4263, better support for nested fixed position elements

diff --git a/src/offset.js b/src/offset.js
index bca01d7..c1cfd86 100644 (file)
--- a/src/offset.js
+++ b/src/offset.js
@@ -23,6 +23,7 @@ else
                        top = elem.offsetTop, left = elem.offsetLeft;
 
                while ( (elem = elem.parentNode) && elem !== body && elem !== docElem ) {
+                       if ( jQuery.offset.supportsFixedPosition && prevComputedStyle.position === "fixed" ) break;
                        computedStyle = defaultView.getComputedStyle(elem, null);
                        top -= elem.scrollTop, left -= elem.scrollLeft;
                        if ( elem === offsetParent ) {
@@ -42,7 +43,7 @@ else
                        top  += body.offsetTop,
                        left += body.offsetLeft;
 
-               if ( prevComputedStyle.position === "fixed" )
+               if ( jQuery.offset.supportsFixedPosition && prevComputedStyle.position === "fixed" )
                        top  += Math.max(docElem.scrollTop, body.scrollTop),
                        left += Math.max(docElem.scrollLeft, body.scrollLeft);
 
@@ -64,6 +65,10 @@ jQuery.offset = {
                this.doesNotAddBorder = (checkDiv.offsetTop !== 5);
                this.doesAddBorderForTableAndCells = (td.offsetTop === 5);
 
+               checkDiv.style.position = 'fixed', checkDiv.style.top = '20px';
+               this.supportsFixedPosition = (checkDiv.offsetTop >= 15); // safari subtracts parent border width here which is 5px
+               checkDiv.style.position = '', checkDiv.style.top = '';
+
                innerDiv.style.overflow = 'hidden', innerDiv.style.position = 'relative';
                this.subtractsBorderForOverflowNotVisible = (checkDiv.offsetTop === -5);