Bug 271956 [Forms] SharedHeaderFormEditor should check for null header
The SharedHeaderFormEditor should be coded to handle null header. A null header may happen in some cases: although it is hard for me to pinpoint the exact cases, I did encounter a NullPointerException resulting from the following method: public boolean isDirty() { return headerForm.isDirty() || super.isDirty(); } I believe a simple null check (defaulting to false) would solve this situation.
bundles/org.eclipse.ui.forms/src/org/eclipse/ui/forms/editor/SharedHeaderFormEditor.java
* 
	 * @param parent
	 *            the page container parent
	 * 
	 * @see org.eclipse.ui.part.MultiPageEditorPart#createPageContainer(org.eclipse.swt.widgets.Composite)
	 */
	protected Composite createPageContainer(Composite parent) {
		parent = super.createPageContainer(parent);
		parent.setLayout(new FillLayout());
		ScrolledForm scform = getToolkit().createScrolledForm(parent);
		scform.getForm().setData(FormUtil.IGNORE_BODY, Boolean.TRUE);
		headerForm = new HeaderForm(this, scform);
		createHeaderContents(headerForm);
		return headerForm.getForm().getBody();
	}
	/**
	 * Returns the form that owns the shared header.
	 * 
	 * @return the shared header
	 */
	public IManagedForm getHeaderForm() {
		return headerForm;
	}
	
	protected void createPages() {
		super.createPages();
		
		
		if (getActivePage() == -1) {