Compositing CGI with Bigger Node Trees - Nuke 101: Professional Compositing and Visual Effects - page 104

Curve1's four Box fields turn light blue, which means you have successfully
linked Crop1's property to CurveTool1's property ( FIGURE 3.11 ).
Figure 3.11. The light blue color of the fields shows there is animation.
Let's learn a little bit more from this and see what this expression looks like.
3. FromCrop1'sBoxproperty'sAnimationmenu,chooseEditExpressiontodisplay
the Expression panel ( FIGURE 3.12 ) .
Figure 3.12. Crop1's Box property's Expression panel.