We'll add a TODO item to possibly add a Style property that would be applied to the rafting windows. Right now you can't just create a blanket Style and put it in the resources for them since the RaftingWindow class is internal to our assembly.
Actually what we ended up doing was adding a protected virtual CreateRaftingWindow method to DockSite. You can call the base method, see if the return value is a Window, and if so, set the properties you mentioned. This will be in the next maintenance release. Sound good?