Lower confidence button

Today, we can set color cell or cross cell.

If i'm stuck, i wood like a button to lower my confidence level. When i click it :

all next set(color or cross) will be marked with some transparency (so i can see i'm not full confident about them)
the first set have a special color to let me remember what choice i've made to lower my confidence level.
if i click to the trash, it will not reset all the level, but only this confidence level (and raise it to the previous one).

I can again use the lower confidence button to lower it again, add some transparency...

How about this feature ?

jaredforrest / nonocross