Here's my (rather shoddy) try:
Just a simple matter of turning the tab image into an alpha mask, then using it on the gradient box. Not too sure about the border though. I guess a lot of things still can't be done in PdN and I don't know too much about Photoshop. Also, the box's border is clipped anyway, so I have no idea what colour it'd be, if you want to be picky
EDIT: accidentally saved without alpha channel