bug in set-frame-position?

[Mickey Ferguson]

>From the documentation:

(set-frame-position FRAME XOFFSET YOFFSET)

Sets position of FRAME in pixels to XOFFSET by YOFFSET.
This is actually the position of the upper left corner of the frame.
Negative values for XOFFSET or YOFFSET are interpreted relative to
the rightmost or bottommost possible position (that stays within the
screen).

Now what I want is to be able to specify my window (frame) to be up against
the right-hand side of my screen.  So I thought I would use (set-frame
position (selected-frame) -0 0).  Nope, it interprets -0 the same as 0.  The
best I could do was -1 0, which left a little space between my window and
the edge of the screen.  Is there any way to specify it flush-right?  Or is
this a bug where it should interpret -0 as meaning flush-right, but it's
not?  Or maybe there's another way to do this?