If I understand you correctly, you would basically need AlwaysOnTop shortcuts on the screen edges (I used to use alwaysontop 1px black labels for this, but currently I configure a conditional jDesk leftmousedown script and pad my desktop area a little so maximized windows won't cover the screen edges).

I'm not sure how the mouse button being pressed fits in. You would either click outside of the hotspot and proceed to moving it into the hotspot, or you would just click the hotspot as if it were any other window. It's possible subclass.dll could work on hotspots but I doubt it.