Index: /CKEditor/trunk/CHANGES.html
===================================================================
--- /CKEditor/trunk/CHANGES.html	(revision 5975)
+++ /CKEditor/trunk/CHANGES.html	(revision 5976)
@@ -142,4 +142,5 @@
 		<li><a href="http://dev.ckeditor.com/ticket/6179">#6179</a> : [WebKit] The Image dialog was not working if the editor didn't receive the focus first.</li>
 		<li><a href="http://dev.ckeditor.com/ticket/4657">#4657</a> : [Opera] Styles where not working with collapsed selections.</li>
+		<li><a href="http://dev.ckeditor.com/ticket/4534">#4534</a> : [Opera] Arrow key to navigate through combo list has side effects of window scrolling.</li>
 		<li><a href="http://dev.ckeditor.com/ticket/5839">#5839</a> : "Insert row after" was removing the ids of the elements from the clicked row.</li>
 		<li><a href="http://dev.ckeditor.com/ticket/6315">#6315</a> : DIV plugin TT #2885 regression.</li>
Index: /CKEditor/trunk/_source/plugins/panel/plugin.js
===================================================================
--- /CKEditor/trunk/_source/plugins/panel/plugin.js	(revision 5975)
+++ /CKEditor/trunk/_source/plugins/panel/plugin.js	(revision 5976)
@@ -171,5 +171,6 @@
 				win.$.CKEDITOR = CKEDITOR;
 
-				doc.on( 'keydown', function( evt )
+				// Arrow keys for scrolling is only preventable with 'keypress' event in Opera (#4534).  
+				doc.on( 'key' + ( CKEDITOR.env.opera? 'press':'down' ), function( evt )
 					{
 						var keystroke = evt.data.getKeystroke(),