It seems that QIntValidator is really signed, so out 1000
to 0xFFFFFFFF limit was equal to 1000 to -1 -- not
allowing any UIN! I changed it to 1000 to 0x1FFFFFFF.
I'm not sure whether it's the right solution (did UINs
overflow 2G?) -- we might need to use a
QRegExpValidator of \d+ and check for <=1000 when
the user presses Ok.