Bug in ticker.py

Hi, I'm posting this to the mailing list first because I'm

    > not sure I've fixed this correctly. This is a patch for a
    > bug in ticker.py.

Another user told me about this one offlist and the fix is in CVS. My
approach was to revert to what we were doing before (which somehow got
lost in translation) which is to set the view lim to be plus/minus 1
the constant value.

Thanks for the patch, anyhow!