Bug 327026 [Compatibility] NPE thrown when reopening an editor after moving a view into the shared area
1. Open an editor. 2. Move the 'Problems' view into the shared area. 3. Close the 'Problems' view. 4. Close the editor. 5. Reopen the same file from step 1. 6. An NPE is thrown. java.lang.NullPointerException at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.getParentWithContext(PartServiceImpl.java:224) at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.internalFixContext(PartServiceImpl.java:272) at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.bringToTop(PartServiceImpl.java:248) at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.showPart(PartServiceImpl.java:742) at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.showPart(PartServiceImpl.java:795) at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2206) at org.eclipse.ui.internal.WorkbenchPage.access$14(WorkbenchPage.java:2173) at org.eclipse.ui.internal.WorkbenchPage$6.run(WorkbenchPage.java:2155) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2151) at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2135) at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2126) at org.eclipse.ui.ide.IDE.openEditor(IDE.java:651) at org.eclipse.ui.ide.IDE.openEditor(IDE.java:610) at org.eclipse.jdt.internal.ui.javaeditor.EditorUtility.openInEditor(EditorUtility.java:354) at org.eclipse.jdt.internal.ui.javaeditor.EditorUtility.openInEditor(EditorUtility.java:164) at org.eclipse.jdt.ui.actions.OpenAction.run(OpenAction.java:219)
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
private IEclipseContext getSubContext(MUIElement element) {
		if (element instanceof MContext) {
			return ((MContext) element).getContext();
		} else if (element instanceof MElementContainer<?>) {
			Object selectedElement = ((MElementContainer<?>) element).getSelectedElement();
			if (selectedElement instanceof MContext) {
				return ((MContext) selectedElement).getContext();
			} else if (selectedElement instanceof MElementContainer<?>) {
				return getSubContext((MUIElement) selectedElement);
			}
		}
		return null;
	}
	private void internalFixContext(MPart part, MUIElement oldSelectedElement) {
		if (oldSelectedElement == null) {
			return;
		}
		MContext parentPart = getParentWithContext(oldSelectedElement);
		if (parentPart == null) {
			
			return;
		}
		IEclipseContext parentContext = parentPart.getContext();
		IEclipseContext oldContext = getSubContext(oldSelectedElement);
		Object child = parentContext.get(IContextConstants.ACTIVE_CHILD);
		if (child == null || oldContext == null || child == oldContext) {
			parentContext.set(IContextConstants.ACTIVE_CHILD,
					part == null ? null : part.getContext());
		}
	}