I do the same thing and it works great in IWP. I did have to make sure that I set the field size to match the graphic (or, at least, the x-y ratio was correct).
If you make small squares in FMP, three colors and white.
and make a global container with four repetitions. And copy and paste the small squares into the repetitions.
and make a number field for flagcalculation
and make a calculation field with a Case Function for 0, 1, 2, 3 contents in flagcalculation number field with a container result.
and make an invisible button to increment the flagcalculation by 1 unless it is 3
You will have a Flag Container field that when clicked on will increment the color code.
Since it is a square solid color, it scales well and is tiny in size.