Try gadgetwidth(), gadgetheight(), clientwidth(desktop()), clientheight(desktop()) and setgadgetshape().
Find the size of the window with gadgetwidth() and gadgetheight(), then find the screensize with clientwidth(desktop()) and clientheight(desktop()), then calculate where the top left pixel should be and use setgadgetshape() to put the window there.
Find the size of the window with gadgetwidth() and gadgetheight(), then find the screensize with clientwidth(desktop()) and clientheight(desktop()), then calculate where the top left pixel should be and use setgadgetshape() to put the window there.