Previously it would react to any selection changed event, which could in lude time changes (which is done by removing then adding the ControlPointGroup). Closes #10590.
If the control point group moved was empty, it would not be created due to a lack of ControlPointInfo.Add() calls.
Prevents attempting to read from the `colours` field before it is actually injected.
We want them to display on all screens with a timeline as they are quite useful in all cases.