Here is an example:
<img src="https://dl.dropboxusercontent.com/u/108499873/temp/Capture1.PNG" border="0" />
If a user hit tab, it would look like this:
<img src="https://dl.dropboxusercontent.com/u/108499873/temp/Capture2.PNG" border="0" />
If a user hit shift + tab:
<img src="https://dl.dropboxusercontent.com/u/108499873/temp/Capture3.PNG" border="0" />