Index: src/main/java/common/javax/swing/plaf/basic/BasicInternalFrameTitlePane.java =================================================================== --- src/main/java/common/javax/swing/plaf/basic/BasicInternalFrameTitlePane.java (revision 490282) +++ src/main/java/common/javax/swing/plaf/basic/BasicInternalFrameTitlePane.java (working copy) @@ -400,13 +400,14 @@ private TitlePaneInternals internals; public BasicInternalFrameTitlePane(final JInternalFrame frame) { + if (frame == null) { + throw new NullPointerException(); + } + this.frame = frame; setBorder(BorderFactory.createEmptyBorder(1, 0, 1, 0)); installInternals(); - - if (frame != null) { - installTitlePane(); - } + installTitlePane(); } protected JMenuBar createSystemMenuBar() {