[plt-scheme] DrScheme Can't Insert Negative Fractions?

On Sun, Aug 31, 2008 at 11:44 AM, Carl Eastlund <cce at ccs.neu.edu> wrote:
> Did you accidentally add 7/9 to -17?  That would give you -16 2/9, as
> you saw.  You need to remember to subtract the 7/9, because it's
> negative too.  Or add -7/9.

The UI seems to expect an input as "you would write it", so -17 2/9.

Is that how the "insert fraction" dialog is implemented, it adds the number?

I didn't find any docs for that.