Originally posted by RBellavance I think I can confirm the problem, even though the only flash I own (a Sigma EF500 DG SUPER flash) does not actually work wirelessly with the K-7.
Simply taking two pictures of myself in front of a mirror, with custom option 31 successively set to each of its possible values (and flash set to wireless, of course!), produces identical images, and the pop-up flash is clearly lit during the exposure in both cases.
Looks like a bug to me, hopefully one that can be fixed in firmware.
With my K10 and AF540 or Metz58 you can see that the (pop-up) flash still emits some light even when it's just a controller. This is normal. It's the final control flash that you see, but it's much less bright than when you use the pop-up in the normal mode.
You should check the difference not in the mirror but by taking an image. With the popup flash as a controller you'll see a single shadow, from the remote wireless flash, in the normal mode you should see two shadows.