Add Keyframes in Timeline using a GUIEditor?

Animating a GameObject using a GUIEditor does not record keyframes.

1. I want to animate a GameObject using the new Timeline feature (in Unity 2017.2).
2. I have added the GameObject to the Timeline.
3. I press the GameObject track's record button.
4. I manipulate the GameObject's attributes directly. Keyframes are added. It works great!
5. To simplify the work-flow I have written a GUIEditor that contains sliders controlling just the attributes I want to animate.
6. When I drag the sliders, the attributes of the GameObject change accordingly. All good!
7. The problem: Even though the GameObject's attributes update, keyframes are not recorded in the Timeline.

Is there a way to force the Timeline to update and add keyframes to any attributes that have changed?

 

No, I have not used the serialized versions. Thank you for pointing that out!