Index: modules/swing/src/main/java/common/javax/swing/plaf/basic/BasicOptionPaneUI.java =================================================================== --- modules/swing/src/main/java/common/javax/swing/plaf/basic/BasicOptionPaneUI.java (revision 490473) +++ modules/swing/src/main/java/common/javax/swing/plaf/basic/BasicOptionPaneUI.java (working copy) @@ -156,6 +156,10 @@ } public Dimension preferredLayoutSize(final Container parent) { + if (parent == null) { + return new Dimension(); + } + int totalWidth = 0; int totalHeight = getMaxChildHeight(parent); int numChildren = parent.getComponentCount();