Ignore the NPE which happens when dropping a rocket component as the

last component in the previous child element.  I can't seem to find a
better solution than to just eat the npe.

swing/src/net/sf/openrocket/gui/main/SwingExceptionHandler.java

@@ -402,6 +402,24 @@ public class SwingExceptionHandler implements Thread.UncaughtExceptionHandler, E
 			}
 		}
 
+		/*
+		 * Detect and ignore DnD bug in component tree - related to 6560955 in Sun JRE.
+		 */
+		if (t instanceof NullPointerException) {
+			StackTraceElement[] trace = t.getStackTrace();
+
+			if (trace.length > 2 &&
+					trace[0].getClassName().equals("javax.swing.tree.TreePath") &&
+					trace[0].getMethodName().equals("pathByAddingChild") &&
+
+					trace[1].getClassName().equals("javax.swing.plaf.basic.BasicTreeUI") &&
+					trace[1].getMethodName().equals("getDropLineRect")) {
+
+				log.warn("Ignoring Sun JRE bug updating drop location " +
+						"(see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6560955): " + t);
+				return true;
+			}
+		}
 		return false;
 	}