In RT-21531:
This is actually the intended behavior - although not specified in the spec. We decided this after the spec was originally written has not been updated since then. Jindra can update it once he is back.

The last time when spec was updated is 12-march.

1. If I call setValue(<some new color>) value is set to property "value", but rectangle and text don't reflect this change. Watch movie1.
2. If I set new color in web-form, and click "use" it is set to property, but it is not reflected by rectangle and text on control. Watch movie2.

Also, I note here, that normal and expected behavior now: when you select new color in custom color dialog, it is set to property, but it is not reflected by rectangle and text on control. But if you click "use" selected color (which is new) should be reflected by rectangle and text on control.