The following screenshot displays control points. One control point, at the top of the curve, has yellow outline because it was selected. It is easy to distinguish the selected control point because the size of all control points has been exaggerated.
If I do not exaggerate the size of the control points, I do not know which control points were selected because only their outline changes color. The rest is white. This flaw can be fixed by changing the display of the selected control points. The best solution, from the user point of view, is blinking all selected objects. The easiest solution, from the programmer point of view, is changing the color of the entire control point (interior and outline).
The same problem exists when the object’s color is yellow, and the same yellow color highlights selected objects. This is why blinking is the best way to highlight all selected objects.
There is similar, but less severe problem with backfaces. I use the following texture for all backfaces. It works, but blinking would be more elegant. Fast blinking would be best for highlighting selected objects. Slow blinking would be best for showing the backfaces.