xeventmanager - part of Simula to Xlib interface
IOProcess class XEventManager(Display);
This class manage input from the Window Server, translate it
to Simula object of the corresponding Event-class, finds out
which Window it is targeted for, and finally, sends it as a
message to the defined subclass of XProcess.
XEventManager also sees to that the buffered output to the
Window Server is flushed when the Simula client program is
about to go idle.
INIT: to be registered by ProcessManager and started.;