The problem with using command line parameters for any application is that a
new instance of the application is started. For some apps it would be
preferable if there was only one instance of the app and the command line
could be forwarded to the previous instance. This can be done by looking for
a previous instance of the app, sending a WM_COPYDATA message to that
previous instance and exiting (if it is found). If it is not found then the
application is started normally. This is the technique used by MS Word and
other applications.

This tip created by Michael Culley. Link is:

Look for the October 2003 Tip of the Month.

VB .Net, C# and VB6 source code is provided.

Larry Rebich