Good day balloni55,
hmm colors may be little confusing here I see.
Exact color you define in "draw circle" screen is only at the thin border of the circle. Color inside of circle is defined as define color + 1/10 of defined color alpha value. So inside the circle it will always be transparent, it just depend on how much. Difference is visible on your screen.
I can imagine decrease this effect little bit if you find it useful. But making whole circle with same defined opacity seems to me little useless. Usually most important is border of circle to just decide if something is inside or outside, right?