Rainbows, and Transition Effects (two blend tutorial drawings shown):
You use Blends to create color and or shape transitions.  No limit to the number of colors or shapes.  The Blend parameter palette, left center, provides convenient direct access to the internal components of the blend group.  No need to "ungroup" to modify a color or line style.

Groups are interactively editable (a Blend is one kind of a Group):
Notice the selected blend (lower center) has controls available for each of the graphic components.  You may edit any component directly and interactively view - real time - the effects of your changes.  To move the whole group, notice the double border, this is a safe area to click-grab-move the whole group.

Highly optimized:
A pleasing high quality rendering of a simple rainbow can require 50 to 200 individual Bezier curves.  EazyDraw uses an advanced anticipatory caching algorithm to provide responsive real time editing - even if you don't have a Dual-Biggy-Hertz system.  Go ahead and grab the download to see how we do on you own Blend requirements.  We do provide automatic or full manual control over the density of the transition curves.