Firefox: unable to access caption with arrow keys

[j.swiderski]

1. Paste in the following code:

   <p>
   	This is some <strong>sample text</strong>. You are using <a href="http://ckeditor.com/">CKEditor</a>.</p>
   <table border="1" cellpadding="1" cellspacing="1" style="width: 500px;">
   	<caption>
   		this is table</caption>
   	<tbody>
   		<tr>
   			<td>
   				&nbsp;</td>
   			<td>
   				&nbsp;</td>
   		</tr>
   		<tr>
   			<td>
   				&nbsp;</td>
   			<td>
   				&nbsp;</td>
   		</tr>
   		<tr>
   			<td>
   				&nbsp;</td>
   			<td>
   				&nbsp;</td>
   		</tr>
   	</tbody>
   </table>
   <p>
   	This is some <strong>sample text</strong>. You are using <a href="http://ckeditor.com/">CKEditor</a>.</p>
   

2. Place the cursor inside the table and try to move it with arrows to reach the caption.

Result: It is impossible to reach the caption with arrow keys but t is possible using mouse.