Index: /CKEditor/trunk/CHANGES.html
===================================================================
--- /CKEditor/trunk/CHANGES.html	(revision 4050)
+++ /CKEditor/trunk/CHANGES.html	(revision 4051)
@@ -233,4 +233,5 @@
 			copy and paste Flash content among different editor instances.</li>
 		<li><a href="http://dev.fckeditor.net/ticket/4193">#4193</a> : Automatic font color produced empty span on Firefox 3.5.</li>
+		<li><a href="http://dev.fckeditor.net/ticket/4186">#4186</a> : [FF] Fixed First open float panel cause host page scrollbar blinking.</li>
 	</ul>
 	<h3>
Index: /CKEditor/trunk/_source/plugins/panel/plugin.js
===================================================================
--- /CKEditor/trunk/_source/plugins/panel/plugin.js	(revision 4050)
+++ /CKEditor/trunk/_source/plugins/panel/plugin.js	(revision 4051)
@@ -79,5 +79,6 @@
 			'<div class="', editor.skinClass ,'"' +
 				' lang="', editor.langCode, '"' +
-				' style="z-index:' + ( editor.config.baseFloatZIndex + 1 ) + '">' +
+				// iframe loading need sometime, keep the panel hidden(#4186).
+				' style="display:none;z-index:' + ( editor.config.baseFloatZIndex + 1 ) + '">' +
 				'<div' +
 					' id=', id,