Priority to active F-curve when extending selection

When multiple f-curves points are superposed, clicking several times iterate in each superposed f-curve.
The iteration is related to the channels order, from top to bottom.

Problem
If we have an f-curve selected (the active one), and we want to select additional points on it with Shift + Click , if it's not top-level in channels, this will add the points of the top-level f-curve instead (X loc in the example below, whereas active is Z loc).

Solution
Extended point selection should always prioritize the active f-curve, as if it were "sent" to top level in channels

If shift + clicking on a point already selected, only then fallback to next f-curve in channel orders.