ptolemy/gui/ExtensionFileFilter.java is used by ptolemy/gui/PtolemyFrame.java and ptolemy/actor/gui/TableauFrame.java. This class is a copy of diva.gui.ExtensionFileFilter so that ptolemy.gui does not require diva.
Note that as of Java 1.6, there is a FileNameExtensionFilter which replaces this class. See http://download.oracle.com/javase/6/docs/api/javax/swing/filechooser/FileNameExtensionFilter.html However, this class can be used with both java.awt.FileDialog and javax.swing.JFileChooser because it implements java.io.FilenameFilter and extends javax.swing.FilenameFilter.
ptolemy/gui/ExtensionFileFilter.java has the following license:
Copyright (c) 1998, 1999 by Sun Microsystems, Inc. All Rights Reserved.
Sun grants you ("Licensee") a non-exclusive, royalty free, license to use, modify and redistribute this software in source and binary code form, provided that i) this copyright notice and license appear on all copies of the software; and ii) Licensee does not utilize the software in a manner which is disparaging to Sun.
This software is provided "AS IS," without a warranty of any kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
This software is not designed or intended for use in on-line control of aircraft, air traffic, aircraft navigation or aircraft communications; or in the design, construction, operation or maintenance of any nuclear facility. Licensee represents and warrants that it will not use or redistribute the Software for such purposes.