Move systray_dock_window call to X11DRV_CreateWindow so that it can
safely call SetWindowPos without having _CheckNotSysLevel crash the
explorer.

This shows that the IRpcStubBuffer for a delegated stub's base
interface is stored at (void**)This-1.

These show that delegated stubs need different Connect, Disconnect and
CountRefs methods than non-delegated stubs (ie they don't use all of
the CStdStubBuffer_* functions).