The %FrontWindowFrame% token returns the frame of the front window (same as %WindowFrame%1%).
The returned array resembles this:
228,23,1314,1173
x1 == 228 y1 == 23 x2 == 1314 y2 == 1173 x1,y1 refers to the upper left corner of the window. x2,y2 refers to the lower right corner of the window.