Scrolls open from the left to the right, delay 2 seconds:

You can also change the direction, changing the parameters to "forward"...

Play with these settings by using the existing "popup apearence" styles any time and get cool effects as you experiment.

Paste this code in the "Add own effect" field.

progid:DXImageTransform.Microsoft.GradientWipe(GradientSize=0.25,wipestyle=0,motion=forward);