Colour selection not working in 4.0

Hi, I have upgraded to the latest release (4.0) and since then the background colour entries in the site colour option menu are not coloured according to the HEX colour code in them and also the colour picker does not appear anymore. From the release notes (which I cannot locate anymore) I seem to remember that this latest release changes the colour display method. Is there a way to reactivate the coloured background and colour picker? Thanks Riccardo