I am using a G3 as my walkaround camera, but I am finding that the design of the rear thumb rest is such that I often end up pressing the ISO button by mistake. I have discovered some unnecessarily high ISOs either when shooting or, worse, during post process. A common problem it would seem judging by the various threads on this forum. The G5 seems to have a much better design in this regard. It occurs to me that this could be resolved by the addition of an external thumb rest, similar to the Thumbs Up for Leica. Does anyone know of anything suitable on the market at a reasonable price?