When we call JDesktopPane.setDesktopManager(new DefaultDesktopManager()) and try to iconify an internalframe, it results in NPE
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at javax.swing.RepaintManager.getVolatileOffscreenBuffer(RepaintManager.java:1030) at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1489) at javax.swing.RepaintManager.paint(RepaintManager.java:1272) at javax.swing.JComponent.paint(JComponent.java:1042) at javax.swing.JComponent.paintChildren(JComponent.java:889) at javax.swing.JComponent.paint(JComponent.java:1065) at com.apple.laf.AquaInternalFrameDockIconUI$ScaledImageLabel.updateIcon(AquaInternalFrameDockIconUI.java:193) at com.apple.laf.AquaInternalFrameDockIconUI$ScaledImageLabel.paint(AquaInternalFrameDockIconUI.java:204) at javax.swing.JComponent.paintChildren(JComponent.java:889) at javax.swing.JComponent.paint(JComponent.java:1065) at javax.swing.JComponent.paintChildren(JComponent.java:889) at javax.swing.JComponent.paint(JComponent.java:1065) at javax.swing.JLayeredPane.paint(JLayeredPane.java:586) it seems the getVolatileOffscreenBuffer() is called with JRootPane component for AquaLookAndFeel because of which SwingUtilities.getWindowAncestor(JRootPane) returns null causing NPE. Fixed by adding a null check. The JInternalFrame can be successfully iconized now after setting DesktopManager. ------------- Commit messages: - Fix - Fix - 8170794: [macosx] Error when using setDesktopManager on a JDesktopPane on MacOS X with Look and Feel Aqua Changes: https://git.openjdk.org/jdk/pull/9408/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9408&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8170794 Stats: 106 lines in 2 files changed: 105 ins; 0 del; 1 mod Patch: https://git.openjdk.org/jdk/pull/9408.diff Fetch: git fetch https://git.openjdk.org/jdk pull/9408/head:pull/9408 PR: https://git.openjdk.org/jdk/pull/9408
