Use tabindex = "- 1" on your "internal button". This will prevent focus.
http://jsfiddle.net/GHgtc/2/
<input placeholder="focus on me then press tab" type="text">
<div id="container">
<a id="inner-button" tabindex="-1" href="#">You can see me !</a>
</div>
UPDATE:
, . z-index: -1, , , javascript.
#inner-button{
display: block;
background: red;
width: 20px;
height: 20px;
position: absolute;
top: 5px;
right: -20px;
z-index:-1;
}
http://jsfiddle.net/GHgtc/3/
, . z-index: 0 .