Index: /CKEditor/trunk/CHANGES.html
===================================================================
--- /CKEditor/trunk/CHANGES.html	(revision 3967)
+++ /CKEditor/trunk/CHANGES.html	(revision 3968)
@@ -182,4 +182,5 @@
 		<li><a href="http://dev.fckeditor.net/ticket/3982">#3982</a> : Fixed enterKey on empty list item result in weird dom structure.</li>
 		<li><a href="http://dev.fckeditor.net/ticket/4101">#4101</a> : Now it is possible to close dialog before gets focus.</li>
+		<li><a href="http://dev.fckeditor.net/ticket/4075">#4075</a> : [IE6/7]Fixed apply custom inline style with "class" attribute failed.</li>
 	</ul>
 	<h3>
Index: /CKEditor/trunk/_source/core/dom/element.js
===================================================================
--- /CKEditor/trunk/_source/core/dom/element.js	(revision 3967)
+++ /CKEditor/trunk/_source/core/dom/element.js	(revision 3968)
@@ -775,5 +775,5 @@
 								// Note : I was not able to reproduce it outside the editor,
 								// but I've faced it while working on the TC of #1391.
-								if ( this.getAttribute( 'class' ) > 0 )
+								if ( this.getAttribute( 'class' ) )
 									return true;
 
Index: /CKEditor/trunk/_source/plugins/styles/plugin.js
===================================================================
--- /CKEditor/trunk/_source/plugins/styles/plugin.js	(revision 3967)
+++ /CKEditor/trunk/_source/plugins/styles/plugin.js	(revision 3968)
@@ -444,5 +444,5 @@
 					if ( parent.getName() == elementName )
 					{
-						for ( var attName in def.attribs )
+						for ( var attName in def.attributes )
 						{
 							if ( styleNode.getAttribute( attName ) == parent.getAttribute( attName ) )
Index: /CKEditor/trunk/_source/tests/core/dom/element.html
===================================================================
--- /CKEditor/trunk/_source/tests/core/dom/element.html	(revision 3967)
+++ /CKEditor/trunk/_source/tests/core/dom/element.html	(revision 3968)
@@ -506,4 +506,16 @@
 			var element = new CKEDITOR.dom.element( document.getElementsByTagName( 'small' )[0] );
 			assert.isTrue( element.hasAttributes() );
+		},
+
+		/**
+		 * Test detecting of 'class' attribute in IE6/7.
+		 */
+		test_hasAttributes_4075 : function()
+		{
+			if ( !CKEDITOR.env.ie && ( CKEDITOR.env.ie7Compat || CKEDITOR.env.ie6Compat ) )
+				return;
+			var element = new CKEDITOR.dom.element( 'span' );
+			element.setAttribute( 'class', 'value' );
+			assert.isTrue( element.hasAttributes(), 'Failed to detect "class" attribute existence.' );
 		},