Convert from device to world coordinates. The variable gin must have members dX and dY set before the call.These represent the coordinates of the point as a fraction of the total drawing area. If the point passed in is on a window then the function returns 1, members wX and wY will be filled with the world coordinates of that point and the subwindow member will be filled with the index of the window on which the point falls. If the point falls on more than one window (because they overlap) then the window with the lowest index is used. If the point does not fall on a window then the function returns 0, wX and wY are set to 0 and subwindow remains unchanged.

This function is not used in any of our C examples.