No, I don't think that's it. The window will shrink to about 1/2 it's size and then you'll see a dark desk top page around it. Jab the cursor into the corner again and the page will go back to its regular size immediately. Jab the cursor into one of the bottom corners and the window will disappear completely, leaving you with the open desk top.
It's a nice feature, but I just want to know which check box I uncheck to make it stop.