I'm sure a lot of people know about this little blue block magnifier but in a previous thread I suggested that this tool could help her and thought others may find it useful also. I use this this design tool all the time when I am planning a quilt and choosing layouts and colors. It is a real time saver and saves on the disappointment factor too, all that for a little over $5.00.
This site shows two viewers, I have the EZ view Magnifier and I don't know about the other one.
I am not affiliated in any way with either the store or the viewer. Just a good little tool.