There will be no need for restraining colorsets if this is made. Basically, you open a GUI, pick a color from the rainbow, and then you can paint stuff with that color. There will be a row of boxes to keep favorites in, and an eyedropper tool to copy the color of any brick.
This is possible because the paintcan won't change colors anymore. Instead, it will emit particles that are the same color as the one you've selected. I've experienced how restraining colorsets can be recently with me and Eksi's Myst project. We only have a few spare colors left, and by then we are screwed. Builds are also getting messed up when transferring between colorsets, as I'm sure everyone knows by now.
So do it, please. In the next update of Blockland, or at least soon. I am a pencil-eating squash meatball. imagine the possibilities.