The cleartext button in the passwordbox doesn't match the one in a textbox

There were some triggers missing. See the screenshot below that illustrates how the cleartext button looks when hovering the mouse over it (on a textbox):

![textbox-mouseover](https://f.cloud.github.com/assets/631724/70614/219e8fb2-5fb5-11e2-9333-1aae4faf3f56.png)
Also, it changes color when pressed (as expected).

Here's a screenshot of the password box, when hovering the button:

![passbox-mouseover](https://f.cloud.github.com/assets/631724/70615/3926e22e-5fb5-11e2-81d5-f15e8f9fbffe.png)

It doesn't look the same. This PR fixes that issue.