The Gain in [Euro in my case] field does not report the conversion of the "Total gain" field as one would expect, but of the total value field.

Is not a mistake per se, but the field should be renominated "Value in" in this case…

Other than that is a wonderful little thingy…

Only one thing could make it better from my point of view: If instead of an application it could exist as a konfabulator widget (Tiger gadget from 10.4) it would be perfect.

If will remain an application in the future, a dynamic icon in the dock (reproducing the "glance" mode) could be a nice idea as well