Instances of this class provide synchronization support
for displays. A default instance is created automatically
for each display, and this instance is sufficient for almost
all applications.
IMPORTANT: Typical application code never
needs to deal with this class. It is provided only to
allow applications which require non-standard
synchronization behavior to plug in the support they
require. Subclasses which override the methods in
this class must ensure that the superclass methods are
invoked in their implementations
IMPORTANT: Typical application code never needs to deal with this class. It is provided only to allow applications which require non-standard synchronization behavior to plug in the support they require. Subclasses which override the methods in this class must ensure that the superclass methods are invoked in their implementations