Index: /CKEditor/trunk/CHANGES.html
===================================================================
--- /CKEditor/trunk/CHANGES.html	(revision 5848)
+++ /CKEditor/trunk/CHANGES.html	(revision 5849)
@@ -58,4 +58,5 @@
 		<li><a href="http://dev.ckeditor.com/ticket/6108">#6108</a> : Fixed div style.</li>
 		<li><a href="http://dev.ckeditor.com/ticket/5336">#5336</a> : Remove object style.</li>
+		<li><a href="http://dev.ckeditor.com/ticket/6155">#6155</a> : [[FF]] Modifying Table Header Properties by selecting first Row, causing several issues.</li>
 	</ul>
 	<h3>
Index: /CKEditor/trunk/_source/plugins/table/dialogs/table.js
===================================================================
--- /CKEditor/trunk/_source/plugins/table/dialogs/table.js	(revision 5848)
+++ /CKEditor/trunk/_source/plugins/table/dialogs/table.js	(revision 5849)
@@ -120,5 +120,5 @@
 				{
 					var selection = editor.getSelection(),
-						bms = editor.getSelection().createBookmarks();
+						bms = selection.createBookmarks();
 				}
 
@@ -167,5 +167,6 @@
 						{
 							var th = theRow.getChild( i );
-							if ( th.type == CKEDITOR.NODE_ELEMENT )
+							// Skip bookmark nodes. (#6155)
+							if ( th.type == CKEDITOR.NODE_ELEMENT && !th.hasAttribute( '_cke_bookmark' ) )
 							{
 								th.renameNode( 'th' );