OK, this title is not meant to be taken too literally. But the fact remains that the Blend IDE does have some useful ways to perform Venn-like operations on graphically rendered data.

First question: Why would you care?  Well, as it turns out, many custom UserControls begin life as simple vector-graphics which are rendered with the Shape tools (pen, pencil, line, etc) and tweaked using the Properties window.

As you are building such a rendering, the IDE will capture pen and pencil strokes using a <Path> element, and members of System.Windows.Shapes for rectangles, circles and lines.  For example, assume the following collection of objects on a WPF main window:

If you were to examine the XAML, you would find something such as the following:

Now, using Blend, you can select multiple shape objects (via  Shift + Click) and then activate the context menu on your selection.  Here you will find a Combine menu tem, which exposes a series of Venn-like operations:

For example, if you were to pick the Unite option for each selected shape, your resulting image would appear as so:

And the previous three elements have been combined into a single <Path> object:

Blend is plump-full of useful shortcuts like these, and I'll post other tidbits over time.

Happy Blending.