changing folder icon in Dolphin

[Giorgio]

In Dolphin every folder is associated to an icon. The icon can be changed but in last version of KDE not all icon can be chosen. For example among System icons choosing folder-red or folder-green or folder-yellow has no effect and the folder keep previous icon.

Rosa 2012.1 Desktop Fresh 64 bit, KDE 4.10.4, Dolhpin 2.2.