Project: Eclipse_Platform_UI
Bug 319127 [Forms] ExpandableComposite NPE with focusGained|focusLost when using NO_TITLE
Reported: 2010-07-07 10:05:04 | Status: resolved fixed

Build Identifier: org.eclipse.ui.forms_3.5.0.v20100427 I'm using an ExpandableComposite inside of a property sheet. When I don't use NO_TITLE as a style, I have no problems with the composite (i.e., expanding it, contracting it, clicking away from the properties, clicking back, etc.) However, when I use NO_TITLE, I eventually start having problems - usually after expanding the section, clicking away (to the diagram) and back again. I'm including the trace below. The NPE is being thrown in both the focusGained() and focusLost() methods inside an inner ExpandableComposite class. It makes sense that these methods would throw an NPE, since they're calling on the textLabel, which hasn't been set because I'm using NO_TITLE. Searching through old bugs, I see bugzilla 171265, which is similar - the fix there including a null check. I suggest just adding a quick check for null in the focusGained() and focusLost() methods, e.g., toggle.addFocusListener(new FocusListener() { public void focusGained(FocusEvent e) { if (textLabel != null) { //new textLabel.redraw(); } //new } public void focusLost(FocusEvent e) { if (textLabel != null) { //new textLabel.redraw(); } //new } }); Note: my current workaround is to use the title, i.e., remove the NO_TITLE style, but set the title to "". Trace of one of the NPEs: !ENTRY org.eclipse.ui 4 0 2010-07-07 09:44:07.312 !MESSAGE Unhandled event loop exception !STACK 0 java.lang.NullPointerException at org.eclipse.ui.forms.widgets.ExpandableComposite$5.focusLost(ExpandableComposite.java:601) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:143) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1058) at org.eclipse.swt.widgets.Control.sendFocusEvent(Control.java:2618) at org.eclipse.swt.widgets.Widget.wmKillFocus(Widget.java:1920) at org.eclipse.swt.widgets.Control.WM_KILLFOCUS(Control.java:4504) at org.eclipse.swt.widgets.Canvas.WM_KILLFOCUS(Canvas.java:434) at org.eclipse.swt.widgets.Control.windowProc(Control.java:4193) at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:341) at org.eclipse.swt.widgets.Display.windowProc(Display.java:4886) at org.eclipse.swt.internal.win32.OS.PeekMessageW(Native Method) at org.eclipse.swt.internal.win32.OS.PeekMessage(OS.java:3024) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3652) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2629) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2593) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2427) at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:670) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:663) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:369) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:600) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:619) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574) at org.eclipse.equinox.launcher.Main.run(Main.java:1407) at org.eclipse.equinox.launcher.Main.main(Main.java:1383) Reproducible: Always Steps to Reproduce: I can't give easy steps to reproduce - this is deep within a set of property sheets, where the expandable composite is used to show the attributes of a referenced item.

Files changed in fix:
bundles/org.eclipse.ui.forms/src/org/eclipse/ui/forms/widgets/ExpandableComposite.java