Force Field Keys

How do I set keys for the strength of a force field in 2.5 ? It does not seem to allow this … it only permits changes in direction.

For example, how do I increase wind strength from 1 to 9 over frames 10 to 20 ?

Using a recent build of 2.5 it works just fine. Put the curser over the strength field and press I to add a keyframe.
wind.blend (65.7 KB)

Easy … but not obvious. Thanks for that.

It’s pretty obvious. Almost everything can be keyframed like this. If you want to keyframe something hover your mouse over the parameter and press I or right mouse click and select add keyframe. A method consistent across the whole interface and an extension of how it currently works for blender 2.49.