Fix: Improved DOM ordering for scrolling tables - colgroup, thead, tfoot

- Fixes DataTables/FixedColumns #8

Author: AllanJard

js/core/core.scrolling.js

@@ -227,18 +227,18 @@ function _fnScrollDraw ( settings )
 	// Remove the old minimised thead and tfoot elements in the inner table
 	table.children('thead, tfoot').remove();
 
-	// Clone the current header and footer elements and then place it into the inner table
-	headerCopy = header.clone().prependTo( table );
-	headerTrgEls = header.find('tr'); // original header is in its own table
-	headerSrcEls = headerCopy.find('tr');
-	headerCopy.find('th, td').removeAttr('tabindex');
-
 	if ( footer ) {
 		footerCopy = footer.clone().prependTo( table );
 		footerTrgEls = footer.find('tr'); // the original tfoot is in its own table and must be sized
 		footerSrcEls = footerCopy.find('tr');
 	}
 
+	// Clone the current header and footer elements and then place it into the inner table
+	headerCopy = header.clone().prependTo( table );
+	headerTrgEls = header.find('tr'); // original header is in its own table
+	headerSrcEls = headerCopy.find('tr');
+	headerCopy.find('th, td').removeAttr('tabindex');
+
 
 	/*
 	 * 2. Take live measurements from the DOM - do not alter the DOM itself!
@@ -418,6 +418,9 @@ function _fnScrollDraw ( settings )
 		divFooterInner[0].style[padding] = bScrolling ? barWidth+"px" : "0px";
 	}
 
+	// Correct DOM ordering for colgroup - comes before the thead
+	table.children('colgroup').insertBefore( table.children('thead') );
+
 	/* Adjust the position of the header in case we loose the y-scrollbar */
 	divBody.scroll();