struct CapabilitiesEvent

The event indicates that one or more capabilities have changed.

Since the capabilities are dependent on the client and its UI, it might not

be possible to change that at random times (or too late). Consequently this

event has a hint characteristic: a client can only be expected to make a

'best effort' in honoring individual capabilities but there are no

guarantees. Only changed capabilities need to be included, all other

capabilities keep their values.