Leaving my original post below, just updated this DB so that X & Y stretching are simultaneous.
Hey everybody, first post. Thanks for all who contribute. This is a dynamic block of window 7/8" wide muntins, in a regular pattern, from 1x2 to 5x5. I keep thinking you should be able to stretch one corner to enlarge it in the X and Y directions, but I'm actually pretty new to this. I did discover that you can have multiple stretch actions on one parameter, and that you can assign a distance multiplier, and I went to town with it. I do think it is silly that stretches will apply to a midpoint of a line and actually move it, which took some tweaking to get that out of this block, but I'm really happy with this. It allows us to very quickly see how different patterns will look on our elevations. Hope it helps someone else.
Cole