How to edit an animated GIF in Photoshop?(Locked- Duplicate thread)

I have an animated GIF that I would like to edit (just change some colors).

I have done this in a GIF Animator. Would this be possible in Photoshop (CS5 Extended)?

In the menu choice (show) Animation, a window at the bottom shows all frames that are in the GIF file.

But I can here only edit the first frame, for the rest of the layers editing is dimmed out.

Is there a way to edit a GIF file in Photoshop (CS5)?

/LarryM