By default Metanet windows work with Scilab in asynchronous mode, i.e. Scilab proceeds without waiting for graphics commands sent to Metanet windows to terminate. This mode is the most efficient. But when running a lots of graphics commands, problems can arise. For instance, you might highlight a set of nodes in a bad Metanet window because the good one has not yet appeared! So it is possible to use a synchronous mode . Then Scilab waits until the functions dealing with the Metanet windows have terminated.
The metanet_sync function is used to change the mode: metanet_sync(0) changes to asynchronous mode (default), metanet_sync(1) changes to synchronous mode, and metanet_sync() returns the current mode (0 = asynchronous, 1 = synchronous).