When you want to color Fences, there are sliders for Transparency, Color Intensity, Tint, and Saturation, similar to the Hue/Saturation sliders in Photoshop.
When you want the Fences to match the exact shade of teal on your background wallpaper, would it not be easier to have a hex or RGB color code box to take the information? Or an eyedropper tool to sample the color you want to make it? (to continue the photoshop comparison)
I would like to request a color code input box (or boxes) in future versions of Fences. It is Officially on my Wish List now.