Index: /CKEditor/trunk/_source/core/dom/node.js
===================================================================
--- /CKEditor/trunk/_source/core/dom/node.js	(revision 7249)
+++ /CKEditor/trunk/_source/core/dom/node.js	(revision 7250)
@@ -671,12 +671,25 @@
 				element = this.getParent();
 
-			if ( element
-					&& typeof element.$.isContentEditable != 'undefined'
-					&& !element.data( 'cke-editable' ) )
-			{
-				return !element.$.isContentEditable;
-			}
+			if ( element && typeof element.$.isContentEditable != 'undefined' )
+				return ! ( element.$.isContentEditable || element.data( 'cke-editable' ) );
 			else
+			{
+				// Degrade for old browsers which don't support "isContentEditable", e.g. FF3
+				var current = element;
+				while( current )
+				{
+					if ( current.is( 'body' ) || !!current.data( 'cke-editable' ) )
+						break;
+
+					if ( current.getAttribute( 'contentEditable' ) == 'false' )
+						return true;
+					else if ( current.getAttribute( 'contentEditable' ) == 'true' )
+						break;
+
+					current = current.getParent();
+				}
+
 				return false;
+			}
 		}
 	}