Larry, I don't think the ask is for a Xara-style Blend.
I took it to be a gradient Fill with colour stops. My attempt is a Linear Fill across all the boxes selected together.
I added in a page background as well.
I could have instead created a lot of black boxes on a white background and placed a large box with colour-stopped fills on top and set it to a Screen (Bleach) Transparency.
Acorn
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