you are right, but this will not do. it makes the detail incorrect in other ways.
right now, the reveal depth is such that the window (frame) sits at the edge of the CMU. If i change the reveal depth making it more shallow and freeing up the brick sill, the window will shift to and incorrect position, sitting halfway on and halfway off the Block.
Since there is nowhere to change the size of the brick sill in depth, i am still convinced that this is a flaw of the window object. This seems like an easy thing to tweak.
Any other ideas?