(Sorry, haven’t yet worked out how to put the images in the right order.)
The third image is the curve editor in Geppetto, a free plugin for DAZ Studio 3. I believe someone is updating it for DAZ Studio 4.5, but it’s not out yet.
The first image is the curve editor inside an aniBlock in aniMate2.
Geppetto allows you to change the interpolation. The second image is with linear interpolation rather than TCB interpolation. There is also a script by Casual, which will probably work in DS4 to change interpolation.
There are no bezier handles, such as you find in most 3d programs.
Geppetto is the best hand animation solution so far - there is also an option to clear the scene, moving the last frame to the first frame. aniMate2 is excellent for pre-made blocks, and for Non-Linear animation. You can use Geppetto to hand animate, then use aniMate2 to create blocks, which will slide along the timeline as necessary, and you can speed them up or slow them down.
I believe all Casual’s scripts will work in DS4, but his plugins won’t. I think he tries to make scripts rather than plugins now for this reason. You can find all his scripts here: