OP can't close threads in RT, only lmod+ can.
Also, to blend colors I like to use a hard round brush with some transparency, and use alt+click to eyedropper the blended color and get a nice gradient. Eg paint some blue, paint some red, then grab a semi-transparent brush and load it with red, then paint some on the blue, eye dropper that, and paint it near the edge of the blended area, etc.