I'm trying to create corrective shape keys using the Driver Editor. I've looked up tutorials on the web but I seem to be the only one who's missing a cursor like in the graph and timeline editor which they were using to animate a corrective shape key.
How do I play the timeline on a Driver Editor?
I'm using Blender 3.0
That cursor is only used as the point of reference for snapping keyframes or inserting new keyframes on the driver curve.
It does not function like a playhead as it does in the F-Curve, Dope Sheet or Timeline editors, because the current "frame" of the driver is given by indirect means: the inputs that you have on that driver.
The only animated visual in the driver editor is that dashed element that shows the current frame as the result of the driver formula. It changes when the driver inputs change (for you to see it animating, the drivers window needs to be selected):
