Since KDE SC 4.4 many hidden options have been added to oxygen to 'fine-tune' the appearance of widgets and window decorations. At the time, they have been made hidden, in order not to scare normal users by facing them with a large number of choices with most of which they would have no idea what to do.
As a drawback, there was a number of bug reports and wishes from advanced users asking for features and configure options which in fact were already there, but not easily accessible. The answer to such reports have been: "edit your configuration file (usually $HOME/.kde4/share/config/oxygenrc), and add this or that line, in this or that section". Not very satisfactory.
For KDE SC 4.5, a new application has been added to remedy the above. It is called oxygen-settings (it runs from either krunner or one's favorite terminal), and provides access to all the previously hidden options. The other advantage of oxygen-settings is that all options for both the widget style and window decoration are regrouped at the same place, fewer clicks away one from the other.
Hopefully this addition will make advanced users happy, without scaring normal users, who would not care about all the functionalities offered here.
Below are a few screenshots of this application.
The first page, corresponding to widgets' style configuration:
The animations page:
It allows to customize each animation used in the widget style independently from the other.
The window decoration page:
It is very similar to what's available in KDE's configuration tool (systemsettings) but includes a number of additional, otherwise hidden, options