Applications which are built with SWT will almost always
require only a single display. In particular, some platforms
which SWT supports will not allow more than one active
display. In other words, some platforms do not support
creating a new display if one already exists that has not been
sent the dispose() message.
In SWT, the thread which creates a Display
instance is distinguished as the user-interface thread
for that display.
All SWT API methods which may only be called from the user-interface
thread are distinguished in their documentation by indicating that
they throw the "ERROR_THREAD_INVALID_ACCESS"
IMPORTANT: This class is not intended to be subclassed.