In the curves UI box, the active item is the same color and the rest of the points, making it almost impossible to know which point is selected.
This can already be solved in the theme for the Properties Editor specifically, but not everywhere else.
We should map this to a theme entry that applies to the entire UI, never mind if you interact with curves via the Properties or anywhere else.
We can use the Active Vertex theme entry for this, in all Editors.
(The same issue applies to the selected color ramp item)