Index: src/main/java/common/java/awt/Container.java =================================================================== --- src/main/java/common/java/awt/Container.java (revision 490131) +++ src/main/java/common/java/awt/Container.java (working copy) @@ -208,6 +208,10 @@ } public Component add(Component comp) { + if (comp == null) { + throw new NullPointerException(); + } + toolkit.lockAWT(); try { // add component to the bottom of the stacking order