Greetings...
Aligning a map to the grid always is a little tricky for me. First I had to realize that the Top-Left corner of the map image should be sized up with the grid you might be using on your image. So, that was quickly taken care of by trimming the edges of my image down.
However, when aligning to the grid, it would be nice if the little yellow box would draw a diagonal red line, when the X & Y (width and height) of the box is perfectly square. Or/and perhaps the box tells you how big it is in pixels while you are drawing it.
Considering that most drawings/maps will be JPGs, perhaps when the yellow drawing box is 216 by 216px (72x3) it would draw a red X from corner to corner, as a default. Thus allowing us to quickly align to a grid of 72x72 pixels.
This will allow people when aligning to grids know exactly that they are drawing a perfect square and not a rectangle a couple of pixels off here or there.