Index: /CKEditor/branches/versions/3.3.x/CHANGES.html
===================================================================
--- /CKEditor/branches/versions/3.3.x/CHANGES.html	(revision 5520)
+++ /CKEditor/branches/versions/3.3.x/CHANGES.html	(revision 5521)
@@ -108,4 +108,5 @@
 		<li><a href="http://dev.fckeditor.net/ticket/5570">#5570</a> : [IE] First enabling SCAYT blind cursor in editor.</li>
 		<li><a href="http://dev.fckeditor.net/ticket/5719">#5719</a> : [IE] 'change' dialog event should not be triggered when dialog is already closed.</li>
+		<li><a href="http://dev.fckeditor.net/ticket/5746">#5746</a> : [Firefox] Form elements (input/textarea) because editable and cause problem in wysiwyg mode.</li>
 		<li>Updated the following language files:<ul>
 			<li><a href="http://dev.fckeditor.net/ticket/5432">#5432</a> : Dutch;</li>
Index: /CKEditor/branches/versions/3.3.x/_source/plugins/htmldataprocessor/plugin.js
===================================================================
--- /CKEditor/branches/versions/3.3.x/_source/plugins/htmldataprocessor/plugin.js	(revision 5520)
+++ /CKEditor/branches/versions/3.3.x/_source/plugins/htmldataprocessor/plugin.js	(revision 5521)
@@ -1,3 +1,3 @@
-/*
+/*
 Copyright (c) 2003-2010, CKSource - Frederico Knabben. All rights reserved.
 For licensing, see LICENSE.html or http://ckeditor.com/license
@@ -85,4 +85,5 @@
 	var defaultDataFilterRules =
 	{
+		elements : {},
 		attributeNames :
 		[
@@ -239,4 +240,19 @@
 			return value.toLowerCase();
 		};
+	}
+
+	function protectReadOnly( element )
+	{
+		element.attributes.contenteditable = "false";
+	}
+	function unprotectReadyOnly( element )
+	{
+		delete element.attributes.contenteditable;
+	}
+	// Disable form elements editing mode provided by some browers. (#5746)
+	for ( i in { input : 1, textarea : 1 } )
+	{
+		defaultDataFilterRules.elements[ i ] = protectReadOnly;
+		defaultHtmlFilterRules.elements[ i ] = unprotectReadyOnly;
 	}
 
Index: /CKEditor/branches/versions/3.3.x/_source/plugins/wysiwygarea/plugin.js
===================================================================
--- /CKEditor/branches/versions/3.3.x/_source/plugins/wysiwygarea/plugin.js	(revision 5520)
+++ /CKEditor/branches/versions/3.3.x/_source/plugins/wysiwygarea/plugin.js	(revision 5521)
@@ -850,4 +850,16 @@
 				} );
 			}
+
+			// Disable form elements editing mode provided by some browers. (#5746)
+			editor.on( 'insertElement', function ( evt )
+			{
+				var element = evt.data;
+				if ( element.type = CKEDITOR.NODE_ELEMENT
+						&& ( element.is( 'input' ) || element.is( 'textarea' ) ) )
+				{
+					element.setAttribute( 'contentEditable', false );
+				}
+			});
+
 		}
 	});