Animate drop down menu

Check this tutorial, not exactly what you want but I think it could help you 

https://www.youtube.com/watch?v=QL1Wb2cyleU

Not really much to it since it's a fixed grid. This could be as trivial as keyframing the box and an invert of fill effect with hold keyframes for the position, possibly bolstered by short opacity keyframes for fade animations of the color change. Really depends on what specific look you're after. Similarly, any expression-driven animation would merely be based on a fixed row index or the quantized position with the only difference being that you'd not animate the position of the highlight but have suitable solids already in place. Then it would be something as trivial as

mCurs=thisComp.layer("Cursor").transform.position[1];

mIndex=3;
mSpace=100;

mLine=mindex*mSpace;

linear(Math.floor(mCurs),mLine,mLine-1,100,0)

or something similar applied to the opacity. Obviously this needs some fiddling and testing, but overall there's really not much more than that to it. It's all just an illusion.

Mylenium