# Linking

Now lets try linking. Lets say we always want these two circles to be the same size. Select two circles, and then select both of their Radius ducks(the cyan dot). Then right click on either duck and a menu will pop up. Click on "Link". Boom. The parameters are linked together. You can prove it to yourself by selecting just one of the circles and changing its radius--the other one will change as well. Neat stuff, eh?

Linking is a fundamental concept in Synfig. You can create links not only between ducks, but also between parameters as well by selecting multiple layers, right clicking on the parameter in the param tab, and selecting "Link".

DIGRESSION: This is how outlines are attached to their regions-but I'm getting ahead of myself. At the moment, the fundamental power and flexibility of linking in Synfig Core is beyond what Synfig Studio currently allows for. This will change in the future. Anyway, back on track...

Lets say you want one of the circles to be a different color. If you look in the toolbox below the tools, you'll see the foreground/background color selector, the outline width selector, and some other stuff like the default blend method and gradient. The foreground/background color widget works exactly as you might expect--you can click on the foreground color, and a modest color chooser will appear. Now to can change the color pretty easily.

But sometimes you just want to click on a color and go. This is where the palette editor tab comes in. It's functionality isn't quite 100% yet (ie: saving and loading custom palettes hasn't been implemented yet), but the default palette is pretty decent. Click on the Palette editor tab and have a look--it's the one with the palette-ish looking icon. Clicking on colors in here will immediately change the default foreground color.

That's all great, but we still haven't changed the color of the circle. There are two ways to do this. The first way is that you select the circle layer you want to modify, goto the params tab and double click on the color parameter--a color selector dialog shows up and you just tweak away. But lets say you already got the color you wanted selected as the default foreground color. Easy. Just click on the "Fill tool" from the toolbox, and then click on the circle in the canvas window. Boom. Circle changes color. This works with more than just circles, but we'll get to that in a sec.

Try playing around with the circles for a bit. Muck around with the parameters, and see what happens. To get you started, play around with feather a bit.