I've got a stroked rectangle and I want only the stroke inside the rectangle to show.
The bottom layer has the stroke over the fill.
The top layer is a duplicate of the bottom layer, except that the fill is black, the fill is over the stroke, and the layer mode is subtract.
Everything looks perfect, EXCEPT there is a thin (one pixel?) line on both the right and left side of the rectangle (where the outside of the stroke would be).
Why are those two thin lines there? Does it have something to do with antialiasing? How ought I make that work right?
Is there a better way to do it?