Function 39, subfunction 1 - get a size of the background image.
Parameters:
- eax = 39 - function number
- ebx = 1 - subfunction number
Returned value:
- eax = [width]*65536 + [height]
Remarks:
- There is a pair function to set sizes of background image -
subfunction 1 of function 15. After which it is necessary,
of course, anew to define image.