Great responses - I agree with NOT doing the drop-over-blade-plunge trick on the T-saw, even though I have this tens of thousands of times over the past 30 years (I used to make a lot of picture frames from plywood and MDF). The T-saw plunge trick is so fast and easy, leaving a nearly perfect edge, so if anyone is ever tempted to do this, do as was suggested by simply raising the blade through the panel while holding it down tight, then push, then lower blade. I have often switched out the 10" blade for a sharp 7-1/4" blade in order to get a closer corner cut, and it is slightly safer. Then simply jig-saw out the panel, and chisel the corners.
john.blazy_dichrolam_llc
Delta Unisaw, Rabbit QX-80-1290 80W Laser, 5 x 12 ft laminating ovens, Powermax 22/44, Accuspray guns, Covington diamond lap and the usual assortment of cool toys / tools.