Anecdote:
On a Windows (2000 or XP, haven't tried Vista) log-on screen, if you
click-and-hold the logon window's titlebar, then press-and-hold
Shift+Down, and leave all 3 held, then after about 5 minutes the
window will reappear from the top, still moving downwards! It's quite
a waste of time though, as you'll have to watch closely because it
will only appear for about 5 seconds.
This is precisely because the position uses 16-bit integers: the
y-coordinate overflows, and after a while returns to the range of
values inside the screen's limits.
The trick is finding how to leave all 3 held for 5 minutes. I used an
empty beer bottle, a marble egg, and a key-chain 
- Tal
ยทยทยท
On 7/19/07, Tim Roberts <timr@probo.com> wrote:
Remember that the Windows GDI was designed when Windows ran on 16-bit
machines. All of the coordinates were signed 16-bit values, ranging
from -32768 to 32767. That limitation still exists in many places in
the interface today.