Bugfix: Property editor window handles closing event properly.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@183 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/userinterface/properties/GUIPropertyEditor.java

@@ -876,6 +876,7 @@ public class GUIPropertyEditor extends javax.swing.JDialog implements ActionList
 	private void closeDialog(java.awt.event.WindowEvent evt)//GEN-FIRST:event_closeDialog
 	{
 		setVisible(false);
+		props.cancelProperty(id);
 		dispose();
 	}//GEN-LAST:event_closeDialog