you could use a circular snake instead of a straight one, so it bows in the way you press, but it never comes straight.. i've seen this on an android snake, i'll give a site if i find one.
that blue isn't a bluescale really, it just overloads the pixels with so much power they seem to be blue. You (sometimes) see that it looks like the place between the pixels dissapears (as they seem to grow) but it really isn't good for your screen..