Index: /CKEditor/branches/versions/3.5.x/_source/plugins/maximize/plugin.js
===================================================================
--- /CKEditor/branches/versions/3.5.x/_source/plugins/maximize/plugin.js	(revision 6224)
+++ /CKEditor/branches/versions/3.5.x/_source/plugins/maximize/plugin.js	(revision 6225)
@@ -199,13 +199,23 @@
 								{
 									overflow : 'hidden',
-									width : 0,
-									height : 0
+									width : ( CKEDITOR.env.opera ? viewPaneSize.width : 0 ) + 'px',
+									height : ( CKEDITOR.env.opera ? viewPaneSize.height - 16 : 0 ) + 'px'
 								};
 
-							mainDocument.getDocumentElement().setStyles( styles );
-							// The fixed position is needed for preventing window scrolls by mouse wheel or focus switch,
-							// even if the scrollbars are not shown (#6747).
-							!CKEDITOR.env.gecko && mainDocument.getDocumentElement().setStyle( 'position', 'fixed' );
-							mainDocument.getBody().setStyles( styles );
+							if ( CKEDITOR.env.ie )
+							{
+								mainDocument.$.documentElement.style.overflow =
+									mainDocument.getBody().$.style.overflow = 'hidden';
+							}
+							else
+							{
+								// Prevent window scrolling, e.g. focus moving outside the editor. (#6747)
+								mainDocument.getDocumentElement().setStyle( 'overflow', 'hidden' );
+								mainDocument.getBody().setStyles( styles );
+							}
+
+							// #4023: [Opera] Maximize plugin
+							if ( CKEDITOR.env.opera )
+								mainDocument.getBody().getParent().setStyles( styles );
 
 							// Scroll to the top left (IE needs some time for it - #4923).