Ticket #4721: 4721_2.patch

_source/plugins/forms/dialogs/checkbox.js

@@ -91 +91 @@
                                                         if ( value && !( CKEDITOR.env.ie && value == 'on' ) )
                                                                 element.setAttribute( 'value', value );
                                                         else
-                                                                element.removeAttribute( 'value' );
+                                                        {
+                                                                if ( CKEDITOR.env.ie )
+                                                                {
+                                                                        // Remove attribute 'value' of checkbox #4721.
+                                                                        var checkbox = new CKEDITOR.dom.element( 'input' );
+                                                                        element.copyAttributes( checkbox, { value: 1 } );
+                                                                        checkbox.replace( element );
+                                                                        editor.getSelection().selectElement( checkbox );
+                                                                        data.element = checkbox;        
+                                                                }
+                                                                else
+                                                                        element.removeAttribute( 'value' );
+                                                        }
                                                 }
                                         },
                                         {