i made something similar to @ten_6044 LUTs
hint: press any key
Your hint should say hold any key! I kept getting momentary flickers of color until I read the code.
It takes a long time for you to respond to key down or key up. There are two reasons. The lesser reason is that the structure
has to be at the point of testing the condition right when you push a key; the major reason is that you are computing four costumes, only one of which you're going to use, each time. Those costumes don't change, so you could just compute them once. I did it this way:
Can you make a virtual button please 
wouldnt changing color effect just be faster
but in my case, i used costumes mapping on costumes
